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PubMed1993

Responses of Bacillus subtilis spores to space environment: results from experiments in space.

Onboard of several spacecrafts (Apollo 16, Spacelab 1, LDEF), spores of Bacillus subtilis were exposed to selected parameters of space, such as space vacuum, different spectral ranges of solar UV-radiation and cosmic rays, applied separately or in combination, and we have studied their survival and genetic changes after retrieval. The spores survive extended periods of time in space--up to several years--, if protected against the high influx of solar UV-radiation. Water desorption caused by the space vacuum leads to structural changes of the DNA; the consequences are an increased mutation frequency and altered photobiological properties of the spores. UV-effects, such as killing and mutagenesis, are augmented, if the spores are in space vacuum during irradiation. Vacuum-specific photoproducts which are different from the 'spore photoproduct' may cause the synergistic response of spores to the simultaneous action of UV and vacuum. The experiments provide an experimental test of certain steps of the panspermia hypothesis.

Bacillus subtilis↗
PubMed1994

Comparison of normal mode analyses on a small globular protein in dihedral angle space and Cartesian coordinate space.

Normal mode analyses on the protein, bovine pancreatic trypsin inhibitor, in dihedral angle space and Cartesian coordinate space are compared. In Cartesian coordinate space it is found that modes of frequencies lower than 30 cm(-1) contribute 80% of the total mean-square fluctuation and are represented almost completely by motions in the dihedral angles. Bond angle and length fluctuations dominate in modes above 200 cm(-1), but contribute less than 2% to the total mean-square fluctuation. In the low-frequency modes a good correspondence between patterns of atomic displacements was found, but on average the root-mean-square fluctuations of the Cartesian coordinate modes are 13% greater than their dihedral angle counterparts. The main effect of fluctuations in the bond angles and lengths, therefore, is to allow the dihedral angles to become more flexible. As the important subspaces determined from the two methods overlap considerably, dihedral angle space analysis can be applied to proteins too large for Cartesian coordinate space analysis.

Journal Article↗
PubMed2004

Space use optimisation and sustainability-environmental assessment of space use concepts.

In this paper, as part of a diptych, we discuss the factor space as a means of improving the environmental performance of building projects. There are indicators for space use efficiency and several more or less broadly supported methods for assessment of environmental issues such as ecological quality, use of building materials and energy consumption. These are discussed in this paper. Assessment methods coupling space use to environmental indicators had not been available until now. Beforehand, plans with different spatial properties could therefore not be environmentally compared. We present a method for the implementation of space use in assessments concerning sustainability. This method was applied to the urban case study presented in our second paper in this journal. In this paper, we also present solutions for improved environmental performance through intensive and multiple use of space in the second, third and fourth dimension.

Cities↗
PubMed2000

Registration of physical space to laparoscopic image space for use in minimally invasive hepatic surgery.

While laparoscopes are used for numerous minimally invasive (MI) procedures, MI liver resection and ablative surgery is infrequently performed. The paucity of cases is due to the restriction of the field of view by the laparoscope and the difficulty in determining tumor location and margins under video guidance. By merging MI surgery with interactive, image-guided surgery (IIGS), we hope to overcome localization difficulties present in laparoscopic liver procedures. One key component of any IIGS system is the development of accurate registration techniques to map image space to physical or patient space. This manuscript focuses on the accuracy and analysis of the direct linear transformation (DLT) method to register physical space with laparoscopic image space on both distorted and distortion-corrected video images. Experiments were conducted on a liver-sized plastic phantom affixed with 20 markers at various depths. After localizing the points in both physical and laparoscopic image space, registration accuracy was assessed for different combinations and numbers of control points (n) to determine the quantity necessary to develop a robust registration matrix. For n = 11, average target registration error (TRE) was 0.70 +/- 0.20 mm. We also studied the effects of distortion correction on registration accuracy. For the particular distortion correction method and laparoscope used in our experiments, there was no statistical significance between physical to image registration error for distorted and corrected images. In cases where a minimum number of control points (n = 6) are acquired, the DLT is often not stable and the mathematical process can lead to high TRE values. Mathematical filters developed through the analysis of the DLT were used to prospectively eliminate outlier cases where the TRE was high. For n = 6, prefilter average TRE was 17.4 +/- 153 mm for all trials; when the filters were applied, average TRE decreased to 1.64 +/- 1.10 mm for the remaining trials.

Humans↗
PubMed1995

CT and MR imaging of the buccal space and buccal space masses.

The authors describe the normal variations in the buccal space and present the range of buccal space pathologic conditions seen on computed tomographic (CT) and magnetic resonance (MR) images. In a series of 50 patients studied with CT and 30 with MR imaging, the visualization and measurement of the normal facial expression and buccinator muscles, parotidomasseteric fascia, parotid duct, accessory parotid tissue, and facial neurovascular bundle were statistically equivalent. The size of the buccal fat pad was statistically the same from side to side within a given patient. Normal lymph nodes were rarely discernible from the facial neurovascular bundles. In a series of 26 patients with unsuspected buccal space masses, salivary gland tumors were the most common masses. Less frequently, benign lesions (eg, hemangioma and dilated parotid ducts) and soft-tissue malignancies (eg, sarcoma) manifested as buccal space masses. Occasionally, a cheek mass of uncertain cause proved to be lymphadenopathy; however, adenopathy is more commonly associated with clinically evident, deeply infiltrating facial neoplasms. Knowledge of the anatomic variations and expected abnormalities of the buccal space is useful for the radiologist interpreting facial CT or MR images.

Adult↗
PubMedDate not supplied

Cluster analysis: significance, empty space, clustering tendency, non-uniformity. II--Empty Space index.

The here presented Empty Space index (ES) evaluates the fraction of the information space without experimental points, i.e. the space where the distance from an experimental point is significantly larger than the mean distance between the experimental points themselves. ES can be used to eliminate the ambiguity of the some clustering indexes, that aim to evaluate the separation of the data set in clusters, but these clustering indexes are really a mixed measure of clustering, of empty space (the empty space does not necessarily correspond to the break between clusters) and of the degree of uniformity of the objects. The ES index can be used also to correct the MST index, the clustering index based on the distribution of edge lengths in the minimum spanning tree connecting the objects. The corrected MST index seems to be a reliable measure of the clustering degree.

Chemistry Techniques, Analytical↗
PubMed1999

Growing crops for space explorers on the moon, Mars, or in space.

An option in the long-duration exploration of space, whether on the Moon or Mars or in a spacecraft on its way to Mars or the asteroids, is to utilize a bioregenerative life-support system in addition to the physicochemical systems that will always be necessary. Green plants can use the energy of light to remove carbon dioxide from the atmosphere and add oxygen to it while at the same time synthesizing food for the space travelers. The water that crop plants transpire can be condensed in pure form, contributing to the water purification system. An added bonus is that green plants provide a familiar environment for humans far from their home planet. The down side is that such a bioregenerative life-support system--called a controlled environment life-support system (CELSS) in this paper--must be highly complex and relatively massive to maintain a proper composition of the atmosphere while also providing food. Thus, launch costs will be high. Except for resupply and removal of nonrecycleable substances, such a system is nearly closed with respect to matter but open with respect to energy. Although a CELSS facility is small compared to the Earth's biosphere, it must be large enough to feed humans and provide a suitable atmosphere for them. A functioning CELSS can only be created with the help of today's advanced technology, especially computerized controls. Needed are energy for light, possibly from a nuclear power plant, and equipment to provide a suitable environment for plant growth, including a way to supply plants with the necessary mineral nutrients. All this constitutes the biomass production unit. There must also be food preparation facilities and a means to recycle or dispose of waste materials and there must be control equipment to keep the facility running. Humans are part of the system as well as plants and possibly animals. Human brain power will often be needed to keep the system functional in spite of the best computer-driven controls. The particulars of a CELSS facility depend strongly on where it is to be located. The presence of gravity on the Moon and Mars simplifies the design for a facility on those bodies, but a spacecraft in microgravity is a much more challenging environment. One problem is that plants, which are very sensitive to gravity, might not grow and produce food in the virtual absence of gravity. However, the experience with growing super-dwarf wheat in the Russian space station Mir, while not entirely successful because of the sterile wheat heads, was highly encouraging. The plants grew well for 123 days, producing more biomass than had been produced in space before. This was due to the high photon flux available to the plants and the careful control of substrate moisture. The sterile heads were probably due to the failure to remove the gaseous plant hormone, ethylene, from the Mir atmosphere. Since ethylene can easily be removed, it should be possible to grow wheat and other crops in microgravity with the production of viable seeds. On the ground Biosphere-2 taught us several lessons about the design and construction of a CELSS facility, but Bios-3 came much closer to achieving the goals of such a facility. Although stability was never completely reached, Bios-3 was much more stable than Biosphere-2 apparently because every effort was made to keep the system simple and to use the best technology available to maintain control. Wastes were not recycled in Bios-3 except for urine, and inedible plant materials were incinerated to restore CO2 to the atmosphere. Since much meat (about 20% of calories) was imported, closure in the Bios-3 experiments was well below 100%. But then, a practical CELSS on the Moon might also depend on regular resupply from Earth. Several important lessons have been learned from the CELSS research described in this review.

Agriculture↗
PubMed1991

The Space Station Freedom Flight Telerobotic Servicer: the design and evolution of a dexterous space robot.

The Flight Telerobotic Servicer (FTS) Project at the Goddard Space Flight Center is developing an advanced telerobotic system to assist in and reduce crew extravehicular activity (EVA) for Space Station) Freedom (SSF). The FTS will provide a telerobotic capability to the Freedom Station in the early assembly phases of the program and will be employed for assembly, maintenance, and inspection applications throughout the lifetime of the space station. Appropriately configured elements of the FTS will also be employed for robotic manipulation in remote satellite servicing applications and possibly the Lunar/Mars Program. In mid-1989, the FTS entered the flight system design and implementation phase (Phase C/D) of development with the signing of the FTS prime contract with Martin Marietta Astronautics Group in Denver, Colorado. The basic FTS design is now established and can be reported on in some detail. This paper will describe the FTS flight system design and the rationale for the specific design approaches and component selections. The current state of space technology and the nature of the FTS task dictate that the FTS be designed with sophisticated teleoperation capabilities for its initial primary operating mode. However, there are technologies, such as advanced computer vision and autonomous planning techniques currently in research and advanced development phases which would greatly enhance the FTS capabilities to perform autonomously in less structured work environments. Therefore, a specific requirement on the initial FTS design is that it has the capability to evolve as new technology becomes available. This paper will describe the FTS design approach for evolution to more autonomous capabilities. Some specific task applications of the FTS and partial automation approaches of these tasks will also be discussed in this paper.

Biomechanical Phenomena↗
PubMed1988

Expansion of extracellular tracer spaces in the isolated heart perfused with crystalloid solutions: expansion of extracellular space, trans-sarcolemmal leakage, or both?

Comparisons of the distributions of tracers putatively confined to the myocardial extracellular space (ECS) in vivo and in isolated hearts perfused with crystalloid solutions via their coronaries, generally indicate that ECS markedly expands--both absolutely and relative to cellular space (ICS)--over a period of in vitro perfusion. Quantification of the expansion is problematic, however, because of the difficulty of distinguishing between a true increase in anatomical ECS and expansion of tracer space due to penetration of the plasma membrane. This difficulty in turn renders an assessment of the distribution of electrolytes and other substances unreliable. In the present study a combined morphometric-tracer distribution analysis is applied towards distinguishing between ECS expansion and tracer leakage in the rat Langendorff preparation perfused with a modified Krebs-Henseleit solution. The results demonstrate that both ICS and ECS expanded with the first few minutes of perfusion, with the ICS remaining constant thereafter and the ECS increment declining slowly. Although the expansion of the ECS initially is disproportionately greater relative to that of the ICS, this relative difference disappears in about 1 h, i.e., the uptake of water by the myocardium is nearly homogeneous. An apparent increase of ECS relative to ICS, by more than one-third the initial space after 90 min perfusion, was found to be entirely artifactual and apparently due to a non-specific increase in sarcolemmal permeability.

Animals↗
PubMed2003

Bursting into space: alterations of sympathetic control by space travel.

AIM: Astronauts return to Earth with reduced red cell masses and hypovolaemia. Not surprisingly, when they stand, their heart rates may speed inordinately, their blood pressures may fall, and some may experience frank syncope. We studied autonomic function in six male astronauts (average +/- SEM age: 40 +/- 2 years) before, during, and after the 16-day Neurolab space shuttle mission. METHOD: We recorded electrocardiograms, finger photoplethysmographic arterial pressures, respiration, peroneal nerve muscle sympathetic activity, plasma noradrenaline and noradrenaline kinetics, and cardiac output, and we calculated stroke volume and total peripheral resistance. We perturbed autonomic function before and during spaceflight with graded Valsalva manoeuvres and lower body suction, and before and after the mission with passive upright tilt. RESULTS: In-flight baseline sympathetic nerve activity was increased above pre-flight levels (by 10-33%) in three subjects, in whom noradrenaline spillover and clearance also were increased. Valsalva straining provoked greater reductions of arterial pressure, and proportionally greater sympathetic responses in space than on Earth. Lower body suction elicited greater increases of sympathetic nerve activity, plasma noradrenaline, and noradrenaline spillover in space than on Earth. After the Neurolab mission, left ventricular stroke volume was lower and heart rate was higher during tilt, than before spaceflight. No astronaut experienced orthostatic hypotension or pre-syncope during 10 min of post-flight tilting. CONCLUSION: We conclude that baseline sympathetic outflow, however measured, is higher in space than on earth, and that augmented sympathetic nerve responses to Valsalva straining, lower body suction, and post-flight upright tilt represent normal adjustments to greater haemodynamic stresses associated with hypovolaemia.

Adult↗
PubMed2005

Implications of the space radiation environment for human exploration in deep space.

Human exploration of the solar system beyond Earth's orbit will entail many risks for the crew on these deep space missions. One of the most significant health risks is exposure to the harsh space radiation environment beyond the protection provided by the Earth's intrinsic magnetic field. Crew on exploration missions will be exposed to a complex mixture of very energetic particles. Chronic exposures to the ever-present background galactic cosmic ray (GCR) spectrum consisting of all naturally occurring chemical elements are combined with sporadic, possibly acute exposures to large fluxes of solar energetic particles, mainly protons and alpha particles. The background GCR environment is mainly a matter of concern for stochastic effects, such as the induction of cancer with subsequent mortality in many cases, and late deterministic effects, such as cataracts and possible damage to the central nervous system. Unfortunately, the actual risks of cancer induction and mortality owing to the very important high-energy heavy ion component of the GCR spectrum are essentially unknown. The sporadic occurrence of extremely large solar energetic particle events (SPE), usually associated with intense solar activity, is also a major concern for the possible manifestation of acute effects from the accompanying high doses of such radiations, especially acute radiation syndrome effects such as nausea, emesis, haemorrhaging or, possibly, even death. In this presentation, an overview of the space radiation environment, estimates of the associated body organ doses and equivalent doses and the potential biological effects on crew in deep space are presented. Possible methods of mitigating these radiations, thereby reducing the associated risks to crew are also described.

Astronauts↗
PubMed2000

Determination of tissue spaces of the isolated hindlimb of the rat using netilmicin as an extracellular space indicator.

The kinetic behaviour of drugs in extracellular space is of interest as it influences the drug's access to, and permanence in, those areas of the body upon which drugs exert pharmacological or toxicological actions. A series of experiments was carried out to characterize the vascular, interstitial and cellular spaces of the isolated hindlimb of the rat. Certain specific experimental conditions were met: body weight was under 230 g to avoid fat tissue in the preparations; a perfusion flow rate of 3 mL min(-1); and 3% of bovine albumin in the perfusate supplied at 25 degrees C to the tissues. The isolation of the hindlimb followed the method described by Ruderman with some modifications to restrict the perfusion to the right hindlimb. Tritiated water, netilmicin and methylene blue were injected separately and efferent fluid samples were collected for 15 min after solute injection. Analysis of the efferent curves was performed to calculate the statistical moments (AUC, area under concentration-time curve; MTT, mean transit time; VTT, variance of mean transit times) and solute distribution volumes, which were subsequently used to estimate the tissue spaces of the isolated hindlimb. The results revealed that methyl blue and netilmicin can be respectively used as alternatives to radiolabelled indicators of the vascular and extracellular spaces of tissues included in the rat isolated hindlimb.

Animals↗
PubMed1995

Dual-task performance in space: results from a single-case study during a short-term space mission.

During spaceflights, astronauts are exposed to many stressors (e.g., microgravity, confinement) that may impair human information-processing capabilities. In order to analyze the possible effects of the space environment on human time-sharing efficiency, a single-case experiment was conducted in which the time course of dual-task performance (unstable tracking with concurrent memory search) of one space crew member was monitored repeatedly (13 times) throughout an 8-day space mission. Tasks were taken from the Advisory Group for Aerospace Research and Development battery of Standardized Tests for Research with Environmental Stressors. Comparisons of in-flight, preflight, and postflight performance revealed no decrements in single-task memory search performance but did reveal clear impairments in single-task tracking and dual-task performance. From these results we conclude that psychomotor processes and higher attentional functions are particularly prone to disturbance effects in space.

Adult↗
PubMedDate not supplied

[Effect of space flight factors on health of cosmonauts in the near and late term after space flights].

Cytogenetical studies of cosmonauts' peripheral blood lymphocytes after space flights on MIR orbital station showed a statistically significant increase in the yields of radiation-induced chromosomal aberrations. However, similar studies with in vitro irradiation of biological objects with accelerated charged particles are of great importance for elucidation of the nature of cytogenetical damage induced in vivo. It is also important to investigate the structure of cosmonatus' diseases over their life, in particular, lens opacities and oncological diseases. Thus, the purpose of the investigations planned is to study cytogenetical damage in blood lymphocytes from cosmonauts after space flights on the ISS in vivo, as well as in donor blood lymphocytes after in vitro exposure to accelerated charged particles. The tasks of the project are as follows: determination of the yields and types of chromosomal aberrations in cosmonauts' blood lymphocytes before and after space flights, comparative studies of biological effects induced in vitro by different types of ionizing radiation in human blood lymphocytes in ground experiments, assessment of cytogenetical risks, analysis of the structure of cosmonatus' diseases comparing with that of whole population, study of the mortality and frequency of cataracts and oncological diseases in cosmonauts. The results to be obtained will be used for setting of health norms applied to the influence of radiations of different types, and for elaboration of measures to reduce health risks from space flight factors.

Astronauts↗
PubMed1985

Space motion sickness and space vestibulology.

Given the relatively short period of the space flight missions and more inexperienced personnel expected to be aloft, if the time in space should be optimized, the critical processes which occur in the body equilibrium system during the period of initial exposure to space environment must be thoroughly investigated. It is most important that improved management of space motion sickness (including the prediction, prevention and countermeasures) is properly developed. The improvement will fully depend on advances in our research on the etiology and pathology of this debilitating condition.

Aerospace Medicine↗
PubMedDate not supplied

[Lipid peroxidation and antioxidant defense system in rats after a 14-day space flight in the "Space-2044" spacecraft].

After 14-day space flight of rats onboard Cosmos 2044 in their blood plasma, homogenates of liver, skeletal muscles and myocardium there were determined the parameters of peroxide oxidation of lipids (POL) and system of antioxidant defense: content of dienic conjugates (DC), malonic dialdehyde (MDA), schiff bases (SB), tocopherol (TF), total antioxidative activity (AOA, only in plasma), activity of antioxidative enzymes (only in tissues) superoxide (SOD), catalase, glutathione-peroxidase (GP), glutathione-reductase (GR). In the animal liver there was a decrease in SB content and an increase of SOD, catalase and GP activities. Skeletal muscles exhibited a reduced SB concentration. In myocardium there was a reduction of DC and SB levels, activity of GR with an increase of TF concentration, activity of SOD and catalase. In the blood plasma there occurred a decline of SB and TF contents and an elevation of MDA and total AOA concentrations. The authors drew a conclusion about a compensated process of POL in the tested animals and about the relation of the observed changes with body response to the final phase of the space mission and acute gravitational stress during a readaptation to the Earth environments. On the basis of the analysis of similar data from shorter-duration space experiments, the noted changes in the parameters of the system of POL and antioxidant defense are considered a universal response which does not directly depend on duration of the orbital phase of a space mission.

Adaptation, Physiological↗
PubMed2004

The potential of the lichen symbiosis to cope with the extreme conditions of outer space II: germination capacity of lichen ascospores in response to simulated space conditions.

Complementary to the already well-studied microorganisms, lichens, symbiotic organisms of the mycobiont (fungi) and the photobiont (algae), were used as "model systems" in which to examine the ecological potential to resist to extreme environments of outer space. Ascospores (sexual propagules of the mycobiont) of the lichens Fulgensia bracteata, Xanthoria elegans and Xanthoria parietina were exposed to selected space-simulating conditions (up to 16 h of space vacuum at 10(-3) Pa and UV radiation at 160 nm < or = lambda < or = 400 nm), while embedded in the lichen fruiting bodies. After exposure, the ascospores were discharged and their viability was tested as germination capacity on different culture media including those containing Mars regolith simulant. It was found that (i) the germination rate on media containing Mars regolith simulant was as high as on other mineral-containing media, (ii) if enclosed in the ascocarps, the ascospores survived the vacuum exposure, the UV-irradiation as well as the combined treatment of vacuum and UV to a high degree. In general, 50 % or more viable spores were recovered, with ascospores of X. elegans showing the highest survival. It is suggested that ascospores inside the ascocarps are well protected by the anatomical structure, the gelatinous layer and the pigments (parietin and carotene) against the space parameters tested.

Ascomycota↗