Search

The pneumatic supporting system consisting of gas springs and self-charged hydrostatic bearings can suppress vibrations and improve durability of free piston Stirling engines. In this paper, a free piston Stirling generator with pneumatic supporting system on the displacer was developed based on a prototype of plated spring scheme. A series of experiments were carried out to evaluate the impacts of self-charging gas bearing on the performance of gas springs. During the experiments, the linear alternator was applied an external AC power supply and the pressure fluctuations in working chamber were ensured to be consistent so that the pneumatic supporting system was separated from the entire engine. Through blocking the orifices and ducts of gas bearings with plugs, the gas springs were decoupled with the gas bearing. Comparative results show that the internally charged hydrostatic bearing can effectively reduce the mechanical damping of the displacer with a reduction from 117 N/m to 83 N/m after the bearing is switched on. While the hydrostatic bearing has side effects on the gas springs that increase the hysteresis loss from 78.48W to 337.11W and decrease the axial stiffness significantly.

Depression is associated with poorer outcomes in a wide spectrum of surgeries but the specific effects of depression in patients undergoing cervical spine surgery are unknown. This study aimed to evaluate the prevalence and impact of pre-surgical clinical depression on pain and other outcomes after surgery for cervical degenerative disc disease using a national representative database. Data of patients with cervical myelopathy and radiculopathy were extracted from the 2005–2014 US Nationwide Inpatient Sample (NIS) database. Included patients underwent anterior discectomy and fusion (ACDF). Acute or chronic post-surgical pain, postoperative complications, unfavorable discharge, length of stay (LOS) and hospital costs were evaluated. Totally 215,684 patients were included. Pre-surgical depression was found in 29,889 (13.86%) patients, with a prevalence nearly doubled during 2005–2014 in the US. Depression was independently associated with acute or chronic post-surgical pain (aOR: 1.432), unfavorable discharge (aOR: 1.311), prolonged LOS (aOR: 1.152), any complication (aOR: 1.232), respiratory complications/pneumonia (aOR: 1.153), dysphagia (aOR: 1.105), bleeding (aOR: 1.085), infection/sepsis (aOR: 1.529), and higher hospital costs (beta: 1080.640) compared to non-depression. No significant risk of delirium or venous thrombotic events was observed in patients with depression as compared to non-depression. Among patients receiving primary surgery, depression was independently associated with prolonged LOS (aOR: 1.150), any complication (aOR:1.233) and postoperative pain (aOR:1.927). In revision surgery, no significant associations were found for prolonged LOS, any complication or pain. In conclusion, in the US patients undergoing ACDF, pre-surgical clinical depression predicts post-surgical acute or chronic pain, a slightly prolonged LOS and the presence of any complication. Awareness of these associations may help clinicians stratify risk preoperatively and optimize patient care. [ABSTRACT FROM AUTHOR]

In our recent survey, the transparent small Lacustrine goby, Gobiopterus lacustris had reported as the endemic species of Luzon, Philippines, was identified as an abundant species in mangroves of Leizhou Peninsula, China. Here, high diversity and significant differentiation of five sites of samples representing the west and east populations were revealed by mitochondrial DNA sequences. Five haplotypes of 56 cytochrome oxidase subunit I (Cox1) with the lengths of 623 base pairs (bp) have the high pairwise identity (>98.8%). Moreover, a total of 31 haplotypes for 129 partial D-loop regions were clustered into two clades corresponding to the east and west sampling sites. The strong population structure was confirmed (ΦST = 0.43017, p < .0001) with high haplotype diversity (h = 0.880 ± 0.017) and low nucleotide diversity (p=.00484). Moreover, both the mismatch distribution analysis and neutral test of D-loop revealed that the west group might experience a recent demographic expansion. Lastly, the isolation-with-migration analysis supported the expansion and indicated that the east-west split happened at approximately 7.1 kyr ago. Given the distribution and diversity, G. lacustris could be a good model for the study of the sea-level fluctuations and coast evolution of the South China Sea. [ABSTRACT FROM AUTHOR]