Cardiovascular effects of simulated zero-gravity in humans

Head-down and head-up [correction of heat-up] tilted bedrest (5 degrees) and head out water immersion (HOWI) for 6 hr were compared. Parameters: Cardiac output (rebreathing method), blood pressure (arm cuff), forearm blood flow (venous occlusion plethysmography), total peripheral (TPR), and forearm vascular (FVR) resistances, Hct, Hb, relative plasma volume (PV) changes, and plasma catecholamines (single-isotope assay). During HOWI there was as expected a decrement in TPR, FVR, Mean arterial pressure (MAP, from 100 to 80 mmHg), Hct, and PV, and--as a new finding--catecholamines, which were 30-50% lower compared with both +5 and -5 degrees bedrest. During head down tilt, MAP was elevated (to 100-110 mmHg) and catecholamines did not fall, while TPR and EVR slowly decreased over 6 hr. HOWI is a stronger stimulus than -5 degrees bedrest, probably because HOWI elevates central venous pressure more markedly emptying the peripheral veins, while bedrest permits a distension of veins, which induces an increase in sympathetic nervous activity.     

Neoplastic transformation of hamster embryo cells by heavy ions

We have studied the induction of morphological transformation of Syrian hamster embryo cells by low doses of heavy ions with different linear energy transfer (LET), ranging from 13 to 400 keV/μm. Exponentially growing cells were irradiated with ¹²C or ²⁸Si ion beams generated by the Heavy Ion Medical Accelerator in Chiba (HIMAC), inoculated to culture dishes, and transformed colonies were identified when the cells were densely stacked and showed a crisscross pattern. Over the LET range examined, the frequency of transformation induced by the heavy ions increased sharply at very low doses no greater than 5 cGy. The relative biological effectiveness (RBE) of the heavy ions relative to 250 kVp X-rays showed an initial increase with LET, reaching a maximum value of about 7 at 100 keV/μm, and then decreased with the further increase in LET. Thus, we confirmed that high LET heavy ions are significantly more effective than X-rays for the induction of in vitro cell transformation.     

Mechanism for assembling antenna in space

The development of large and precise space antennas is one of the most important topics in constructing space infrastructures. We evaluated an approach to assembling large and accurate space antennas which uses space robots. The assembly mechanism was launched together with the ETS-VII, the first telerobotic satellite from Japan, and its performance, including fully automatic assembling, was verified. The assembling-type antenna and the results of antenna assembly experiments are discussed     

Cardiovascular and hormonal responses to bicycle exercise during lower body negative pressure

The purpose was to combine bicycle exercise and LBNP as a model to investigate the mechanisms regulating circulation during gravitatiobal stresses. METHODS: Cardiac Output (CO) by acetylene-, argon-, oxygen rebreathing; Heart Rate (HR) from ECG; Mean Arterial Pressure (MAP) by arm cuff; Plasma Nor-Epinephrine (NE), Epinephrine (E), and Lactate (HLa) by isotope and enzymatic techniques respectively. Total Peripheral Resistance (TPR)=MAP/CO and stroke volume (SV)=CO/HR. Six subjects exercised at 180–200 Watts in the upright position on a mechanically braked computer controlled small bicycle ergometer placed in a LBNP box. The above parameters were measured at rest and at 5 and 9 min of exercise without and with LBNP at −30 or −40 mmHg (depending on LBNP tolerance). RESULTS AND CONCLUSIONS: In the face of an increased sympathetic nervous activity (Ne+E, TPR, and HR increased) during exercise in LBNP, there was a decrease in CO and SV indicating that the venous return was insufficient. However, HLa was unchanged demonstrating that the blood flow to the working muscles did not suffer.     

ETS-II Experiments Part II: Earth Station Facilities

A part of the Earth station at the Kashima Branch of the Radio Research Laboratories has a highly sensitive receiving system newly designed for receiving 3 coherent and weak beacon signals transmitted from the Engineering Test Satellite Type-II (ETS-II) of Japan and obtaining propagation data on quasimillimeter and millimeter wavelengths. The ground system includes a main receiving station which has a 10-m diameter antenna for multifrequencies, highly sensitive receivers, a rain radar, which has many unique functions, a radiometer, meteorological instruments, and data processing computers. The facilities of the main receiving station for ETS-II propagation experiments, except for the rain radar, are described.     

Land mobile satellite propagation experiments in Kyoto City

In February of 1990, land mobile satellite propagation experiments were conducted in Kyoto City, Japan, using the Engineering Test Satellite V (ETS-V). The signal transmitted from the satellite was received and recorded at a mobile unit moving in different streets of the downtown area. The streets chosen have typical downtown medium and high rise buildings, electric utility poles, trees, etc., which caused obstruction to the satellite line of sight. The propagation characteristics such as fade/nonfade distribution, joint fade and nonfade distribution, phase distribution, and their dependence on the antenna type are discussed for the measured link. Error characteristics in digital communication for the above link have been qualitatively analyzed on the basis of the measured signal level fluctuation. Effect of interleaving and coding to improve the communication link is also discussed     

Self-consistent Simulations of Alfv��n Wave Driven Winds from the Sun and Stars

We review our recent results of Alfvén wave-driven winds. First, we present the result of self-consistent 1D MHD simulations for solar winds from the photosphere to interplanetary region. Here, we emphasize the importance of the reflection of Alfvén waves in the density stratified corona and solar winds. We also introduce the recent Hinode observation that might detect the reflection signature of transverse (Alfvénic) waves by Fujimura and Tsuneta (Astrophys. J. 702:1443, 2009). Then, we show the results of Alfvén wave-driven winds from red giant stars. As a star evolves to the red giant branch, the properties of stellar winds drastically change from steady coronal winds to intermittent chromospheric winds. We also discuss how the stellar evolution affects the wave reflection in the stellar atmosphere and similarities and differences of accretion disk winds by MHD turbulence.     

Capability for ozone high-precision retrieval on JEM/SMILES observation

We estimate the capability of ozone (O₃) retrieval with the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) instrument attached to the Exposed Facility of the Japanese Experiment Module (JEM) on the International Space Station (ISS). SMILES carries a 4-K mechanical refrigerator to cool superconducting devices in space. Since SMILES has high sensitivity thanks to the superconducting receiver, it is expected that SMILES has ability to retrieve O₃ profiles more precisely than the previous millimeter–submillimeter limb measurements from satellites.