Liquid water is considered to be critical for life. Gibbs free energy is another factor that is important to sustain life for long durations. Gibbs free energy is obtained by reactions between reductants and oxidants, or from any other non-equilibrium state of matter. As an example, aerobic organisms use carbohydrates and oxygen to obtain energy. Many types of chemoautotrophic mechanisms are known for this process as well. On the surface of Mars, methane and oxidative compounds such as ferric oxide, sulfate and perchloride, which could provide redox-derived Gibbs free energy, have been detected. Iron-dependent methane oxidizing bacteria have been found in marine environments on Earth. This finding suggests the possible presence of methane-oxidizing bacteria on the Mars surface, if the local thermal environment and other resources permit proliferation and metabolism of bacteria. Our project aims to search for methane-oxidizing microbes on the Mars surface. Martian soil will be sampled from a depth of about 5 - 10 cm below the surface, where organisms are expected to be protected from the harsh hyper-oxidative environment of the Mars surface. Small particles less than 0.1 mm or 1 mm will be sieved from the sample, before being transferred to the analysis section by a micro-actuator. The particles will be stained with a cocktail of fluorescent reagents, and examined by fluorescence microscopy. A combination of fluorescent dyes has been selected to identify life forms in samples. A membrane-specific dye or a combination of dyes will be used to detect membranes surrounding the "cell". An intercalating fluorescent dye such as SYBR Green will be used to detect genetic compounds such as DNA. A substrate dye that emits fluorescence upon cleavage by a catalytic reaction will be used to detect the catalytic activity of the "cell". A combination of staining reagents has been chosen based on the definition of life. A membrane separating a cell from the ambient environment may lead to identification of an "individual". DNA or genetic material is required for "replication" of the life form. Catalytic reactions carried out by enzymes drive "metabolism". This combination of strategies will also be useful for detecting pre-biotic organic material as well as remnants of ancient life. Hydrolysis of the polymers in the "cell" followed by HPLC or soft ionization MS for amino acid analysis will be effective for examining whether Martian life is identical to or different from terrestrial life. The number and type of the amino acids as well as their chirality will be analyzed to distinguish whether the polymers are contaminants from Earth.

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Physical activity is known to enhance the mechanical competence of bones. However, previous related studies provide little information regarding the optimum exercises for the prevention of osteoporosis in the lumbar region, including the hip joints. Physical activities can be evaluated by simultaneously collecting acceleration data from accelerometers worn on different parts of the body. We attached three triaxial accelerometers to the ankle, knee, and lumbar points of 20 young women subjects in order to perform acceleration measurements while walking (a flat surface and a stairway) and jumping rope. The acceleration at the lumbar point while walking a flat surface, ascending stairs, and descending stairs were 1.96 ± 0.28, 1.92 ± 0.29, and 2.88 ± 0.66G, respectively. On the other hand, jumping rope provided an acceleration of 5.4G at the lumbar point. This value is higher than the threshold acceleration necessary to induce an osteogenic response in the lumbar region of young subjects, namely 3.5G. Descending stairs provided the second-highest intensity of acceleration in the lumbar region; however, it also produced excess impact acceleration at the ankle and knee points. Jumping rope, in contrast, provided sufficient intensity of acceleration in the lumbar region, but the acceleration imparted to the ankle and knee points remained at a tolerable level. Moreover, correlation analyses of the acceleration at the ankle, knee, and lumbar points during each physical activity showed that the knee joints solely regulated the strong landing impact force while the subjects were descending the flight of stairs. In comparison, while jumping rope, the ankle and hip joints regulated the large landing impact force cooperatively, without overloading themselves. Our results suggest that jumping rope can provide sufficient acceleration to induce an osteogenic response in the lumbar region without causing an overload to any joints. Thus, jumping rope is one of the most optimum exercises for bone mineral gain in the proximal femur and lumbar vertebrae regions in young subjects.

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The aim of this study was to evaluate psycho-physiological effects of two postures on emotional states, in relation to the autonomic responses obtained from measures of heart rate variability and salivary cortisol. This study compared a sitting posture with a 7 degree head-down-tilted (7° HDT) condition. The study assessed anxiety states during the HDT conditions. Twenty-eight healthy volunteers (university students) participated (age = 20.9±1.5). The participants were divided into two groups, high-anxiety and normal, based on state trait anxiety inventory (STAI) scores. A simple protocol for monitoring electrocardiograms (ECGs) was applied for all participants, such that they first quietly adopted the sitting posture for 20 minutes, followed by a subsequent 7° HDT posture was then assumed on a tilting bed for another 20 minutes. At the end of each period, a saliva sample was collected from the participant to measure cortisol concentration and salivary buffering action. Affect-grid scoring was applied to evaluate participant's emotional states. Heart rate variability was calculated to evaluate the balance of autonomic nervous system activities (LF/HF). When the HDT posture was assumed, the high anxiety group showed significantly higher salivary cortisol levels, increases in 0.39 ± 0.35 μg/dl from 0.24 ± 0.22 μg/dl (p<0.05), as well as LF/HF ratios when compared to the sitting posture, increases in 32.68 ± 42.98 from 6.89 ± 9.80 (p<0.05). However, salivary buffering action did not show any significant changes across the postures or groups. Participant's emotion, both of pleasantness and arousal, showed significant changes between postures. These results suggest that the STAI is a useful component of a psycho-physiological evaluation gravitational tolerance and/or adaptability to a microgravity environment.

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A number of parabolic flight experiments have shown that processes within the central nervous system (CNS) are affected by weightlessness in humans. However, it is likely that the changes in the CNS observed during parabolic flights are not solely due to the repeated changes in gravity experienced during the flight. Instead, these changes may be related to secondary psychophysiological reactions related to the emotional and physical stress during these flights. Arginine vasopressin (AVP) acts synergistically with corticotropin-releasing hormone to stimulate corticotropin release from the anterior pituitary, and it is critical in the regulation of hypothalamic-pituitary-adrenal axis activity, a major component of the stress response. The purpose of this study was to elucidate whether stress-related humoral factors, namely, AVP, were altered in human blood exposed to gravity-changing stress. Parabolic flight-naive subjects were exposed to gravity-changing stress eight times during repeated parabolic maneuvers performed by an airplane. Concentrations of AVP, cortisol, and catecholamines were increased just after the parabolic flight without hematocrit alterations. The results of the present study suggest that the plasma concentration of AVP behaves as a stress hormone and might be a sensitive humoral marker for psychophysiological stress in humans.

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