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Jin S. Kang,Jeffery T. King,Christopher R. Anderson,Michael H. Sanders 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.4
As CubeSats have become hugely popular in the recent years, the demand on their capability has also increased. As the missions and functionalities become more complex, coupled with the popular VHF and UHF bands becoming less accessible, CubeSats have been getting pushed into using higher frequency bands. For more capable CubeSats such as NASA and military satellites, utilization of S- and X-band communication have become a common place. While S- and X-band communication provide much higher data rate for the mission, the power and attitude control demand has also increased. Meeting this increased cost and demand on resources may not be feasible for university-level projects as attitude control systems can often cost more than the rest of the CubeSat. This research revisits passive magnetic pointing as an option for providing antenna pointing capability for CubeSats, enabling S- and X-band communication without requiring an active attitude control system. CubeSats can make contact with ground stations located at higher latitude to establish data link with directional antennas. The analyses shows that a higher data throughput can be achieved using S- and X-band communication over the traditional 9600 bps link with the proposed setup, without requiring active attitude control or deployable solar panels. The study characterizes the expected communication link performance for a typical 3U CubeSat when implementing the proposed communication architecture using a S- or X-band patch antenna taking into consideration the expected pointing performance and power generation capability of a 3U CubeSat.
Correlation of Early Outcomes and Intradiscal Interleukin-6 Expression in Lumbar Fusion Patients
John D. Koerner,Dessislava Z. Markova,Greg D. Schroeder,Christopher L. Antonacci,Joseph Mendelis,Alexander R. Vaccaro,D. Greg Anderson,Chris K. Kepler 대한척추신경외과학회 2020 Neurospine Vol.17 No.1
Objective: To determine if there is correlation between intradiscal levels of interleukin-6 (IL-6) and early outcome measures in patients undergoing lumbar fusion for painful disc degeneration. Methods: Intervertebral disc tissue was separated into annulus fibrosus/nucleus pulposus and cultured separately in vitro in serum-free medium (Opti-MEM). Conditioned media was collected after 48 hours. The concentration of IL-6 was quantified using enzyme-linked immunosorbent assay. Pearson correlation coefficients quantified relationships between IL-6 levels and pre- and postoperative visual analogue scale (VAS) back pain and Oswestry Disability Index (ODI), as well as change in VAS/ODI. Results: Sixteen discs were harvested from 9 patients undergoing anterior lumbar interbody fusion (mean age, 47.4 years; range, 21–70 years). Mean preoperative and 6-month postoperative VAS were 8.1 and 3.7, respectively. Mean preoperative and postoperative ODI were 56.2 and 25.6, respectively. There were significant positive correlations between IL-6 expression and postoperative VAS (ρ=0.38, p=0.048) and ODI (ρ=0.44, p=0.02). No significant correlations were found between intradiscal IL-6 expression and preoperative VAS (ρ=-0.12, p=0.54). Trends were seen associating IL-6 expression and change in VAS/ODI (ρ=-0.35 p=0.067; ρ=-0.34, p=0.08, respectively). A trend associated IL-6 and preoperative ODI (ρ=0.36, p=0.063). Conclusion: The direct association between IL-6 expression and VAS/ODI suggests patients with elevated intradiscal cytokine expression may have worse early outcomes than those with lower expression of IL-6 after surgery for symptomatic disc degeneration.