RESUMO
Due to its significance in astrobiology, assessing the amount and state of liquid water present on Mars today has become one of the drivers of its exploration. Subglacial water was identified by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) aboard the European Space Agency spacecraft Mars Express through the analysis of echoes, coming from a depth of about 1.5 km, which were stronger than surface echoes. The cause of this anomalous characteristic is the high relative permittivity of water-bearing materials, resulting in a high reflection coefficient. A determining factor in the occurrence of such strong echoes is the low attenuation of the MARSIS radar pulse in cold water ice, the main constituent of the Martian polar caps. The present analysis clarifies that the conditions causing exceptionally strong subsurface echoes occur solely in the Martian polar caps, and that the detection of subsurface water under a predominantly rocky surface layer using radar sounding will require thorough electromagnetic modeling, complicated by the lack of knowledge of many subsurface physical parameters. Higher-frequency radar sounders such as SHARAD cannot penetrate deep enough to detect basal echoes over the thickest part of the polar caps. Alternative methods such as rover-borne Ground Penetrating Radar and time-domain electromagnetic sounding are not capable of providing global coverage. MARSIS observations over the Martian polar caps have been limited by the need to downlink data before on-board processing, but their number will increase in coming years. The Chinese mission to Mars that is to be launched in 2020, Tianwen-1, will carry a subsurface sounding radar operating at frequencies that are close to those of MARSIS, and the expected signal-to-noise ratio of subsurface detection will likely be sufficient for identifying anomalously bright subsurface reflectors. The search for subsurface water through radar sounding is thus far from being concluded.
RESUMO
Between February 2012 and March 2014 10 patients were admitted to the Affiliated Hospital of Nantong University for surgery due to a thumb tip defect. Nine of these patients were male and one was female and there were 7 cases of left thumb defects and 3 cases of right thumb defects. The surgical procedures followed were first, modification of the flap tail to an equilateral triangle, which facilitated pedicle suturing of soft tissue defects, caused mild tension and effectively reduced venous disorders, and second complete opening of the flap pedicle to the soft tissue defects at the tunnel. All patients were followed up at 6 and 12 months after surgery. Grip and pinch strength were measured 6 and 12 months after surgery. Static two-point discrimination testing of the modified flap showed minor differences from the uninjured hand. Post-surgery grip and pinch strength were restored to approximately 85% of the level of that in the uninjured hand. The modified dorsoulnar artery pedicle flap provided excellent thumb tip defect coverage and is an effective and safe technique for the restoration of grip and pinch strength to the hand after the repair of a thumb tip defect.
RESUMO
On 3 January 2019, China's Chang'E-4 (CE-4) successfully landed on the eastern floor of Von Kármán crater within the South Pole-Aitken Basin, becoming the first spacecraft in history to land on the Moon's farside. Here, we report the observations made by the Lunar Penetrating Radar (LPR) onboard the Yutu-2 rover during the first two lunar days. We found a signal penetration at the CE-4 landing site that is much greater than that at the CE-3 site. The CE-4 LPR images provide clear information about the structure of the subsurface, which is primarily made of low-loss, highly porous, granular materials with embedded boulders of different sizes; the images also indicate that the top of the mare basal layer should be deeper than 40 m. These results represent the first high-resolution image of a lunar ejecta sequence ever produced and the first direct measurement of its thickness and internal architecture.
RESUMO
BACKGROUND: The purpose of this study was to compare outcomes between allograft reconstruction and hook plate fixation for acute dislocation of the acromioclavicular joint with a minimum 2-year follow-up. METHODS: A retrospective comparative study of patients treated for acute acromioclavicular joint dislocation from February 2010 to December 2014 in our hospital, consisting of 16 patients who were followed-up, was performed. Eight patients were treated for acute AC dislocation and underwent surgical reconstruction as follows: the coracoclavicular and acromioclavicular ligaments were reconstructed with the allogenic tendon. The other eight patients were treated with hook plates to maintain the AC joint reset. At the latest follow-up, radiographic analysis and the Constant and University of California-Los Angeles (UCLA) scores were used to evaluate shoulder function. The satisfaction of the patients in terms of the efficacy and visual analog scale (VAS) data were also recorded. RESULTS: After an average follow-up of 30.3 months (range 24-46 months), no patient had dislocated their joint again at the final follow-up based on X-ray examination. The Constant score was 94.4 for the allogenic tendon group and 93.8 for the hook plate group (P = 0.57). According to the UCLA scale (P = 0.23) or VAS (P = 0.16), we found no significant difference between the two groups. All patients reported that they were very satisfied or satisfied with the outcome of surgery, and no significant difference (P = 0.08) was found between the two groups. CONCLUSIONS: The use of allogenic tendon for reconstruction of the coracoclavicular and acromioclavicular ligaments shows excellent outcomes in terms of the recovery of clinical function or radiographic outcomes for acute AC dislocation. Compared with the hook plate, the hardware did not need to be removed.
