Search

Ice-penetrating radar (IPR) imaging is a valuable tool for observing the internal structure and bottom of ice sheets. Subglacial water bodies, also known as subglacial lakes, generally appear as distinct, bright, flat, and continuous reflections in IPR images. In this study, we collect and generate a dataset of one-dimensional reflector waveform features from IPR images of the Gamburtsev Subglacial Mountains region in the CReSIS database, to investigate these features. We apply a deep learning method to reconstruct the reflector features, and subsequently downsample the features to a low-dimensional vector representation. An unsupervised clustering method is then used to separate different types of reflector features, including a reflector type corresponding to subglacial water bodies. The derived clustering labels are used to detect features of subglacial water bodies in IPR images. Using this method, we compare the new detections with the known lakes inventory. The results indicate that this new method identified additional subglacial lakes that were not previously detected, and some previously known lakes are found to correspond to other reflector clusters. This method can offer automatic detections of subglacial lakes and provide new insight for subglacial studies.

Corynebacterium accounts for around 20% of the armpit microbiome and plays an essential role in axillary osmidrosis (AO). In this study, the effects of Lactobacillus bulgaricus treatment on the microecological environment of armpits and its efficacy in the treatment of AO were investigated. A total of 10 AO patients were enrolled in this study. The patients were treated with L. bulgaricus mixed with saline on the left armpit (experimental group) and pure saline on the right armpit (control group) for 28 days. After treatment, AO severity showed a significant decrease (p = 0.013) in the experimental group compared with the control group, and the Corynebacterium abundance also showed a corresponding significant decrease (p < 0.01). Moreover, no significant variation in Staphylococcus abundance was found between these two groups. The microbe diversity is not disturbed in the treatment. Accordingly, our study demonstrates that L. bulgaricus can serve as an effective probiotic microbe for AO treatment by reducing the abundance of Corynebacterium and rebalancing the microecological environment.

Traveltime tomography is a technique to reconstruct acoustic, seismic, or electromagnetic wave-speed distributions from first arrival traveltime data. The ray paths that should be used for tomographic techniques strongly depend on the wave-speed distribution. In this paper, a new method is proposed for finding out the ray paths from Fermat's principle, that means the traveltime of the ray path should be a minimum value. The problem of finding out the ray path is actually an optimum problem. Our new method uses the idea to find out the shortest path in a weighted directed graph to solve the problem. The ray paths found out by this method are used in the iterative reconstruction algorithm. Computer simulation result produced by this reconstruction algorithm is better than that by the conventional ones. It also shows that the new algorithm is effective with good convergency and stability.

Ice-sheet development in Antarctica was a result of significant and rapid global climate change about 34 million years ago. Ice-sheet and climate modelling suggest reductions in atmospheric carbon dioxide (less than three times the pre-industrial level of 280 parts per million by volume) that, in conjunction with the development of the Antarctic Circumpolar Current, led to cooling and glaciation paced by changes in Earth's orbit. Based on the present subglacial topography, numerical models point to ice-sheet genesis on mountain massifs of Antarctica, including the Gamburtsev mountains at Dome A, the centre of the present ice sheet. Our lack of knowledge of the present-day topography of the Gamburtsev mountains means, however, that the nature of early glaciation and subsequent development of a continental-sized ice sheet are uncertain. Here we present radar information about the base of the ice at Dome A, revealing classic Alpine topography with pre-existing river valleys overdeepened by valley glaciers formed when the mean summer surface temperature was around 3 degrees C. This landscape is likely to have developed during the initial phases of Antarctic glaciation. According to Antarctic climate history (estimated from offshore sediment records) the Gamburtsev mountains are probably older than 34 million years and were the main centre for ice-sheet growth. Moreover, the landscape has most probably been preserved beneath the present ice sheet for around 14 million years.