Su-Cheol Han

A DESIGN STUDY OF 100㎓ BAND LOCAL OSCILLATOR SYSTEM BY USING YIG OSCILLATOR

In this paper, we make a design study for a local oscillator system of the 100 ㎓ band cosmic radio receiving system. We use the YIG oscillator with digital driver which is the main oscillator. This oscillator has a good frequency and phase stability at some temperature variation, and the easy computer aided control characteristics. This total system designed to two subsystem, first is the oscillator system include YIG oscillator, tripler, harmonic mixer and triplexer etc., second is the PLL system to supply the precise and stable local oscillator frequency to mixer. The proposed local oscillator system in this paper can be used in a single or multi pixel receiver because this system can be lock the local oscillator frequency automatically using PC.

Visual stimulation-induced mild stress enhances cognitive behavior in cynomolgus monkey

Cortisol is a well-known endogenous glucocorticoid that serves as a stress indicator. It is normally released under stressful condition to warn about imminent danger and thus is critical for survival of the species. However, it is unclear how cortisol relates to cognitive process under physiological condition in high-order primates such as non-human primates (NHP). Here, we report that a slight but significant increase in blood cortisol level by mild stress is positively correlated with the cognitive function in cynomolgus monkey. We stimulated 3 groups of monkeys by viewing consecutive series of pictures of monkeys, pictures of humans, or animation still pictures. We first found that the blood cortisol level was significantly higher during the stimulation session and returned to normal after stimulation session. Among the three types of pictures, the monkeys which were stimulated with monkey pictures showed the most significant increase in cortisol level during stimulation. Furthermore, the monkeys showed significantly enhanced manipulation, suggesting that cortisol affected cognitive processes. Overall, our study demonstrates that visual stimulation both increases blood cortisol and enhances manipulating behavior. Therefore, unlike the common notion that cortisol is a stress indicator, our data supports that a mild increase of cortisol enhances cognition in NHP.

Simplified adaptor for stereotactic surgery in non-human primates

BACKGROUND It is challenging for researchers performing stereotactic procedures to transition from small animals to non-human primate (NHP) experiments. The NHP stereotactic atlas is based on ear-bar zero (EBZ), which is an anatomical reference frame that is not visible during surgery. Most current NHP stereotactic systems require high-cost MRI or CT imaging and complex computer processing to determine the stereotactic coordinates, limiting the procedure to those with significant expertise. NEW METHOD We have designed a simplified adaptor consisting of a circular arc for coronal tilt, a carrier for electrodes or cannulas, and an anchor to attach the adaptor to a conventional stereotactic frame. Our adaptor allows easy identification of the EBZ with the help of an anchor notch, and provides digital distance sensors without the need for imaging data or computer processing. Our system enables the use of trajectories that avoid injury to important structures and vessels. RESULTS We tested the accuracy of our system using simulated targeting with phantoms, and demonstrated sub-millimeter accuracy. Infusion of methylene blue also showed satisfactory staining in target structures deep in the brain. COMPARISON WITH EXISTING METHODS This system does not require high-cost imaging and extra training to determine EBZ. Once EBZ is set automatically by the system itself, targeting is similar to that in small animal stereotactic procedure. CONCLUSION Our simple adaptor will aid researchers who plan to conduct experiments involving stereotactic surgery in NHPs.

Repeated injection of KMRC011, a medical countermeasure for radiation, can cause adverse health effects in cynomolgus monkeys: Possible toxicity of KMRC011, a medical countermeasure for radiation

High‐dose radiation‐induced tissue damage is a major limiting factor in the medical application of nuclear technology. Herein, we tested 28‐day repeated‐dose toxicity of KMRC011, an agonist of toll‐like receptor (TLR) 5, which is being developed as a medical countermeasure for radiation, using cynomolgus monkeys. KMRC011 (0.01, 0.02 or 0.04 mg/kg/day) was intramuscularly injected once daily for 4 weeks, and each two monkeys in both control and 0.04 mg/kg/day group were observed for an additional 2‐week recovery period. There were no dose‐related toxicological changes in mortality, clinical observations, body weight, food consumption, ophthalmological findings, electrocardiographs, coagulation, serum chemistry, organ weights, or urinalysis and urine chemistry. Although treatment‐related changes, such as increased white blood cells, increased absolute and relative neutrophils, decreased relative lymphocytes and inflammatory lesions, were noted in the maximum dose group, these findings were not observed after the 2‐week recovery period. Further, we considered that the kidneys and heart may be target organs of TLR5 agonists, as well as the spleen, and that autophagic signals can be triggered in tissue damage and the repair process. Importantly, accumulation of p62 protein, an indicator of autophagy, and a decrease of caveolin‐1 protein, a regulator of TLR5 protein half‐life, were found in both tissues from the highest dose group. Therefore, we conclude that the no‐observed‐adverse‐effect level for KMRC011 may be greater than 0.04 mg/kg/day in male and female monkeys. Additionally, we propose that further studies are needed to identify the molecular signals, which are related to KMRC011‐induced adverse effects.