Mechanisms associated with the rapid decline in sea ice cover around a stranded ship in the Lazarev Sea, Antarctica

In the satellite data era starting from 1979, the extent of Antarctic sea ice increased moderately for the first 37 years. However, the extent decreased to record low levels from 2016 to 2020, with the drop being greatest in the Weddell and Lazarev Seas of the Southern Ocean. An important question for the scientific fraternity and policymakers is to understand what ocean-atmospheric processes triggered such a rapid decline in sea ice. We employ in-situ, satellite, and atmospheric reanalysis data to examine the causative mechanism of anomalous sea ice variability in the Lazarev Sea at a time of ice growth in the annual cycle (March-April 2019), when a cargo ship was stuck in extensive ice cover and freed following the unusual decline in sea ice. High-resolution Sentinel-1 synthetic aperture radar captured a distinct view of the ship location and track within extensive ice cover of fast sea ice, dense pack ice, and icebergs in the Lazarev Sea on 27 March 2019. Subsequently, the sea ice cover declined and reached the fourth lowest extent in the entire satellite record during April 2019 which was 25.6% lower than the long-term mean value of 2.65 × 10⁶ km². We show that the anomalous sea ice variability was due to the occurrence of eastward-moving polar cyclones, including a quasi-stationary explosive development that impacted sea ice through extreme changes in ocean-atmospheric conditions. The cyclone-induced dynamic (poleward propagation of ocean waves and ice motion) and thermodynamic (heat and moisture plumes from midlatitudes, ocean mixed layer warming) processes coupled with high tides provided a conducive environment for an exceptional decline in sea ice over the region of ship movement.

Testing urine samples with rK39 strip as the simplest non-invasive field diagnosis for visceral leishmaniasis: an early report from eastern India

BACKGROUND

Diagnosis of visceral leishmaniasis (VL) is a major obstacle in the control of this disease. The rK39 strip-test using patient's blood is a breakthrough; however, it still requires a blood sample, which is a concern for safety in the field. We tried to simplify the test using the patient's urine instead of blood.

AIMS

To observe the sensitivity and specificity of the urine test in comparison with the blood test.

MATERIALS AND METHODS

We tested active and post-treatment VL patients, Post Kala azar dermal leishmaniasis (PKDL), VL/HIV and control subjects (healthy, disease suspects and diseased other than VL) with the rK39 strip-test using blood and urine samples.

STATISTICAL ANALYSIS

The level of agreement between the urine and blood testing was calculated by inter-rater agreement (kappa) statistics.

RESULTS

Forty-two active VL, 40 treated VL, six PKDL, three VL/HIV and 139 controls (54 healthy, 21 disease suspects and 64 diseased other than VL) were tested. All VL-related cases showed positive results with urine as well as blood samples (100%). The urine testing was found to have 100% sensitivity and 86.33% specificity for the diagnosis of VL. Kappa statistic between the two methods was 0.916 (P<0.001). Urine testing had more false-positive results in comparison with blood testing (13.67% vs. 9.45%), but the test subjects were from VL-endemic areas and they might be exposed to Leishmania donovani infection.

CONCLUSIONS

The present study has the potentiality of providing a new, yet simplest non-invasive screening tool for VL in remote rural areas.