Water: A Critical Material Enabling Space Exploration

Water is one of the most critical materials in human spaceflight. The availability of water defines the duration of a space mission; the volume of water required for a longduration space mission becomes too large, heavy, and expensive for launch vehicles to carry. Since the mission duration is limited by the amount of water a space vehicle can carry, the capability to recycle water enables space exploration. In addition, water management in microgravity impacts spaceflight in other respects, such as the recent emergency termination of a spacewalk caused by free water in an astronaut's spacesuit helmet. A variety of separation technologies are used onboard spacecraft to ensure that water is always available for use, and meets the stringent water quality required for human space exploration. These separation technologies are often adapted for use in a microgravity environment, where water behaves in unique ways. The use of distillation, membrane processes, ion exchange and granular activated carbon will be reviewed. Examples of microgravity effects on operations will also be presented. A roadmap for future technologies, needed to supply water resources for the exploration of Mars, will also be reviewed

Modeling dopaminergic and other processes involved in learning from reward prediction error: contributions from an individual differences perspective

Phasic firing changes of midbrain dopamine neurons have been widely characterized as reflecting a reward prediction error (RPE). Major personality traits (e.g., extraversion) have been linked to inter-individual variations in dopaminergic neurotransmission. Consistent with these two claims, recent research (Smillie et al., 2011; Cooper et al., 2014) found that extraverts exhibited larger RPEs than introverts, as reflected in feedback related negativity (FRN) effects in EEG recordings. Using an established, biologically-localized RPE computational model, we successfully simulated dopaminergic cell firing changes which are thought to modulate the FRN. We introduced simulated individual differences into the model: parameters were systematically varied, with stable values for each simulated individual. We explored whether a model parameter might be responsible for the observed covariance between extraversion and the FRN changes in real data, and argued that a parameter is a plausible source of such covariance if parameter variance, across simulated individuals, correlated almost perfectly with the size of the simulated dopaminergic FRN modulation, and created as much variance as possible in this simulated output. Several model parameters met these criteria, while others did not. In particular, variations in the strength of connections carrying excitatory reward drive inputs to midbrain dopaminergic cells were considered plausible candidates, along with variations in a parameter which scales the effects of dopamine cell firing bursts on synaptic modification in ventral striatum. We suggest possible neurotransmitter mechanisms underpinning these model parameters. Finally, the limitations and possible extensions of our general approach are discussed

High impact activities in parks: best management practice and future research

Off-road driving, horseriding, rock climbing and similar activities can be lucrative for tour operators and important for local recreational groups, but contentious for management of national parks and protected areas, both because of safety and liability and because of potentially high environmental impacts. These include spreading weeds and pathogens, starting fires and crushing bird nests on beaches, amongst many others. In Australia as elsewhere, off-road vehicles and horses are allowed only in some places in some parks, and often only under permit. We have very little reliable scientific information to-date on just how serious these impacts may be, and on how well they might be managed through minimal-impact practices such as vehicle washdowns, stockfeed processing and seasonal closures. Such information can only be obtained through site specific ecological studies of the plants, animals and watercourses likely to be affected, differentiating tourism impacts from natural causes and fluctuations. This report examines management strategies for these activities worldwide and in Australia. Suggestions for best management practice and future research agendas are set

Mapping the cellular electrophysiology of rat sympathetic preganglionic neurones to their roles in cardiorespiratory reflex integration:A whole cell recording study in situ

Sympathetic preganglionic neurones (SPNs) convey sympathetic activity flowing from the CNS to the periphery to reach the target organs. Although previous in vivo and in vitro cell recording studies have explored their electrophysiological characteristics, it has not been possible to relate these characteristics to their roles in cardiorespiratory reflex integration. We used the working heart–brainstem preparation to make whole cell patch clamp recordings from T3–4 SPNs (n = 98). These SPNs were classified by their distinct responses to activation of the peripheral chemoreflex, diving response and arterial baroreflex, allowing the discrimination of muscle vasoconstrictor-like (MVC(like), 39%) from cutaneous vasoconstrictor-like (CVC(like), 28%) SPNs. The MVC(like) SPNs have higher baseline firing frequencies (2.52 ± 0.33 Hz vs. CVC(like) 1.34 ± 0.17 Hz, P = 0.007). The CVC(like) have longer after-hyperpolarisations (314 ± 36 ms vs. MVC(like) 191 ± 13 ms, P < 0.001) and lower input resistance (346 ± 49  MΩ vs. MVC(like) 496 ± 41 MΩ, P < 0.05). MVC(like) firing was respiratory-modulated with peak discharge in the late inspiratory/early expiratory phase and this activity was generated by both a tonic and respiratory-modulated barrage of synaptic events that were blocked by intrathecal kynurenate. In contrast, the activity of CVC(like) SPNs was underpinned by rhythmical membrane potential oscillations suggestive of gap junctional coupling. Thus, we have related the intrinsic electrophysiological properties of two classes of SPNs in situ to their roles in cardiorespiratory reflex integration and have shown that they deploy different cellular mechanisms that are likely to influence how they integrate and shape the distinctive sympathetic outputs

Power subsystem automation study

The purpose of the phase 2 of the power subsystem automation study was to demonstrate the feasibility of using computer software to manage an aspect of the electrical power subsystem on a space station. The state of the art in expert systems software was investigated in this study. This effort resulted in the demonstration of prototype expert system software for managing one aspect of a simulated space station power subsystem