Temporal variation of Seismic coda wave attenuation in the Virunga volcanic region before the eruption of Nyamulagira of 06 November 2011, Democratic Republic of Congo

Five periods characterize the temporal variation of the quality factor of seismic coda waves attenuation Q_C^(-1)(Q_0^(-1)) at 9 Hz and lapsed time of 30 seconds, before the Nyamulagira eruption of 6 November 2011 in the Virunga volcanic region of eastern Democratic Republic of Congo. The period I (January March 2011) was characterized by low attenuation. It grows during period II (April August 2011) to reach a maximum on the period III (September October 2011) and decreases during period IV (01 06 November 2011). A significant decrease in attenuation characterizes the period V (7 November 2011 January 2012). An average attenuation growth preceded the magmatic eruption for about 7 months, with a transitional period (III) of maximum attenuation less than 2 months (46 days) before. This period corresponds to the emplacement of the magma in a confined storage area or into a shallow magma chamber and the creation of new fractures/cracks. A drop of attenuation is observed two days before the eruption after a total saturation of the fluid in fractures/cracks (period IV). Periods (I III and IV V) correspond respectively to the magmatic intrusion and eruption. The variation of the frequency parameter of Coda wave n indicates a change in the degree and dimension of fracturing over time. The significant differences between periods illustrate the change in volcanic activity in the Virunga region

Intra-Crater Eruption Dynamics at Nyiragongo (D.R. Congo), 2002–2021

Nyiragongo is one of the rare volcanoes on Earth hosting a lava lake. However, the understanding of its plumbing and lava lake systems remains limited, with, until recently, only sporadic or time-limited historical observations and measurements. Combining dense accurate lava lake and crater floor level measurements based on 1,703 satellite radar images and topographic reconstructions using photogrammetry, we obtain the first reliable picture and time evolution of intra-crater erupted lava volumes between the two last flank eruptions in January 2002 and May 2021. The filling of the crater by lava, initiated in 2002 and continued up to May 2021, is seen as an evidence of a long-term pressure build up of the magmatic system. This filling occurs through irregular pulsatory episodes of rising lava lake level, some of which overflow and solidify on the surrounding crater floor. Pauses of stable molten lava lake level and sudden numerous level drops also marked the summit's eruptive activity. The joint analysis with seismic records available since 2015 revealed that the largest lava lake drops are synchronous with seismic swarms associated with deep magma intrusions, generally preceded by an increase of extrusion rate within the crater. The appearance of a spatter cone in the summit crater in 2016, most likely superficially branched to the lava lake, was a clear marker of the change in eruption dynamics. This first long-term time series of Nyiragongo's crater topography between two hazardous flank eruptions might further help to better decipher Nyiragongo's past and future behavior using multi-parameter observations

Role of flow cytometry immunophenotyping in the diagnosis of leptomeningeal carcinomatosis

PURPOSE: To explore the contribution of flow cytometry immunophenotyping (FCI) in detecting leptomeningeal disease in patients with solid tumors. EXPERIMENTAL DESIGN: Cerebrospinal fluid (CSF) samples from 78 patients who received a diagnosis of epithelial-cell solid tumors and had clinical data suggestive of leptomeningeal carcinomatosis (LC) were studied. A novel FCI protocol was used to identify cells expressing the epithelial cell antigen EpCAM and their DNA content. Accompanying inflammatory cells were also described. FCI results (positive or negative for malignancy) were compared with those from CSF cytology and with the diagnosis established by the clinicians: patients with LC (n = 49), without LC (n = 26), and undetermined (n = 3). RESULTS: FCI described a wide range of EpCAM-positive cells with a hyperdiploid DNA content in the CSF of patients with LC. Compared with cytology, FCI showed higher sensitivity (75.5 vs 65.3) and negative predictive value (67.6 vs 60.5), and similar specificity (96.1 vs 100) and positive predictive value (97.4 vs 100). Concordance between cytology and FCI was high (Kp = 0.83), although misdiagnosis of LC did not show differences between evaluating the CSF with 1 or 2 techniques (P = .06). Receiver-operator characteristic curve analyses showed that lymphocytes and monocytes had a different distribution between patients with and without LC. CONCLUSION: FCI seems to be a promising new tool for improving the diagnostic examination of patients with suspicion of LC. Detection of epithelial cells with a higher DNA content is highly specific of LC, but evaluation of the nonepithelial cell compartment of the CSF might also be useful for supporting this diagnosis

Naive and memory CD4+ T-cells in the cerebrospinal fluid of children with aseptic meningitis following measles-mumps-rubella vaccination and enteroviral meningitis

We investigated the distribution of memory (CD45RO+) and naive (CD45RA+CD62L+) CD4+ T-cells as well as CD8+ T-cells and total T-cells in the CSF of children with aseptic meningitis following measles-mumps-rubella (MMW) vaccination and those with enteroviral meningitis. Flow cytometric analysis of CSF cells was performed in 12 children with MMR vaccine-associated meningitis and 11 children with enteroviral meningitis. Percentages of total T-cells, CD4+ and CD8+ T-cells and monocytes in CSF of patients from the two groups were not significantly different. The majority of CD4+ T-cells in the CSF of both patient groups were of memory phenotype. Percentages of CSF naive CD4+ T-cells were increased in children with aseptic meningitis following MMR vaccination. Further studies focused on the more detailed immunophenotyping of CSF cells are needed to fully establish the usefulness of flow cytometry in the diagnostic workup of inflammatory CNS diseases in children

Local infrasound monitoring of lava eruptions at Nyiragongo volcano (D.R. Congo) using urban and near-source stations

During eruptions, volcanoes produce air-pressure waves inaudible for the human ear called infrasound, which are very helpful for detecting early signs of magma at the surface. Compared to violent ash-rich explosions, recording more discrete atmospheric disturbances from effusive eruptions remains a practical challenge depending on the distance to the source. At Nyiragongo volcano (D.R. Congo), towering above a 1-million urban area, we analyzed local infrasonic records between January 2018 and April 2022. An acoustic signature from this open-vent volcano is detected up to the volcano observatory facilities in Goma city center about 17 km from its crater. We compared infrasound signals with space-based observations of the intra-crater activity (SO2 emissions, thermal anomalies, crater depth/radius). We thus obtain a comprehensive picture of Nyiragongo's eruptive activity during this period, encompassing the drainage of its lava lake during its third known flank eruption on 22 May 2021