Spaceflight Control Research Articles

Integrated analysis of miRNAome and transcriptome reveals that microgravity induces the alterations of critical functional gene modules via the regulation of miRNAs in short-term space-flown C. elegans

Microgravity, as a unique hazardous factor encountered in space, can induce a series of harmful effects on living organisms. The impact of microgravity on the pivotal functional gene modules stemming from gene enrichment analysis via the regulation of miRNAs is not fully illustrated. To explore the microgravity-induced alterations in critical functional gene modules via the regulation of miRNAs, in the present study, we proposed a novel bioinformatics algorithm for the integrated analysis of miRNAome and transcriptome from short-term space-flown C. elegans. The samples of C. elegans were exposed to two space conditions, namely spaceflight (SF) and spaceflight control (SC) onboard the International Space Station for 4 days. Additionally, the samples of ground control (GC) were included for comparative analysis. Using the present algorithm, we constructed regulatory networks of functional gene modules annotated from differentially expressed genes (DEGs) and their associated regulatory differentially expressed miRNAs (DEmiRNAs). The results showed that functional gene modules of molting cycle, defense response, fatty acid metabolism, lysosome, and longevity regulating pathway were facilitated by 25 down-regulated DEmiRNAs (e.g., cel-miR-792, cel-miR-65, cel-miR-70, cel-lsy-6, cel-miR-796, etc.) in the SC vs. GC groups, whereas these modules were inhibited by 13 up-regulated DEmiRNAs (e.g., cel-miR-74, cel-miR-229, cel-miR-70, cel-miR-249, cel-miR-85, etc.) in the SF vs. GC groups. These findings indicated that microgravity could significantly alter gene expression patterns and their associated functional gene modules in short-term space-flown C. elegans. Additionally, we identified 34 miRNAs as post-transcriptional regulators that modulated these functional gene modules under microgravity conditions. Through the experimental verification, our results demonstrated that microgravity could induce the down-regulation of five critical functional gene modules (i.e., molting cycle, defense response, fatty acid metabolism, lysosome, and longevity regulating pathways) via the regulation of miRNAs in short-term space-flown C. elegans.

Sleep Disruption, Fatigue, and Altered Neurobehavioral Performance Among Flight Controllers During Spaceflight Operations

In spaceflight operations, flight controllers manage technical aspects of spaceflight control and spacecraft systems. The flight control team is a group subjected to shift work. Acute and chronic exposure to shift work has been associated with circadian misalignment, sleep impairment, and a negative impact on cognitive performance. This study aims to review the effects of shift work on sleep, circadian rhythms, mood, and cognitive performance of flight controllers during real and simulated spaceflight operations. Shift work during low-Earth orbit spaceflight missions is associated with a reduction in alertness, motivation, processing speed, and working memory performance efficiency. Flight controllers also report excessive insomnia and insufficient total sleep time. The development of shift work sleep disorder may be present in up to 40% of workers, especially among night and evening shift workers. Mars operations and Mars-simulated missions are associated with an impairment of visual-motor performance, working memory efficiency, and reaction time. Between 50%–87% of controllers can synchronize their circadian rhythm to a Mars day (24.65 hours), although this adaptation is not reflected in improved neurobehavioral performance.

Microgravity alters the expressions of DNA repair genes and their regulatory miRNAs in space-flown Caenorhabditis elegans

During spaceflight, multiple unique hazardous factors, particularly microgravity and space radiation, can induce different types of DNA damage, which pose a constant threat to genomic integrity and stability of living organisms. Although organisms have evolved different kinds of conserved DNA repair pathways to eliminate this DNA damage on Earth, the impact of space microgravity on the expressions of these DNA repair genes and their regulatory miRNAs has not been fully explored. In this study, we integrated all existing datasets, including both transcriptional and miRNA microarrays in wild-type (WT) Caenorhabditis elegans that were exposed to the treatments of spaceflight (SF), spaceflight control with a 1g centrifugal device (SC), and ground control (GC) in three space experiments with the periods of 4, 8 and 16.5 days. The results of principal component analysis showed the gene expression patterns for five major DNA repair pathways (i.e., non-homologous end joining (NHEJ), homologous recombination (HR), mismatch repair (MMR), nucleotide excision repair (NER), and base excision repair (BER)) were well separated and clustered between SF/GC and SC/GC treatments after three spaceflights. In the 16.5-days space experiment, we also selected the datasets of dys-1 mutant and ced-1 mutant of C. elegans, which respectively presented microgravity-insensitivity and radiosensitivity. Compared to the WT C. elegans flown in the 16.5-days spaceflight, the separation distances between SF and SC samples were significantly reduced in the dys-1 mutant, while greatly enhanced in the ced-1 mutant for five DNA repair pathways. By comparing the results of differential expression analysis in SF/GC versus SC/GC samples, we found the DNA repair genes annotated in the pathways of BER and NER were prominently down-regulated under microgravity during both the 4- and 8-days spaceflights. While, under microgravity, the genes annotated in MMR were dominatingly up-regulated during the 4-days spaceflight, and those annotated in HR were mainly up-regulated during the 8-days spaceflight. And, most of the DNA repair genes annotated in the pathways of BER, NER, MMR, and HR were up-regulated under microgravity during the 16.5-days spaceflight. Using miRNA-mRNA integrated analysis, we determined the regulatory networks of differentially expressed DNA repair genes and their regulatory miRNAs in WT C. elegans after three spaceflights. Compared to GC conditions, the differentially expressed miRNAs were analyzed under SF and SC treatments of three spaceflights, and some altered miRNAs that responded to SF and SC could regulate the expressions of corresponding DNA repair genes annotated in different DNA repair pathways. In summary, these findings indicate that microgravity can significantly alter the expression patterns of DNA repair genes and their regulatory miRNAs in space-flown C. elegans. The alterations of the expressions of DNA repair genes and the dominating DNA repair pathways under microgravity are possibly related to the spaceflight period. In addition, the key miRNAs are identified as the post-transcriptional regulators to regulate the expressions of various DNA repair genes under microgravity. These altered miRNAs that responded to microgravity can be implicated in regulating diverse DNA repair processes in space-flown C. elegans.

Matrix metalloproteinases in extracellular matrix remodeling: molecular, cellular and tissue aspects

Matrix metalloproteinases are an integral component of the organ-specific tissue microenvironment, primarily participating in the regulation of the state of the integrative-buffer metabolic environment, tissue remodeling, morphogenesis and immunogenesis, and the genesis of pathological vascular diseases. Therefore, issues related to regulation of matrix metalloproteinase activity under altered gravity are a matter of high urgency for space biomedicine. The review highlights aspects of regulation of matrix metalloproteinase activity under altered gravity. The study results included in the current systematic review were searched for in independent literature sources in the PubMed and Cochrane databases, Google Scholar and the NASA Technical Reports Server. A variety of stress factors associated with space flights, in particular, exposure to radiation, enhances the expression of transforming growth factor beta and matrix metalloproteinases-2. Experimental data obtained during several flights demonstrate that microgravity affects the architecture of cells and increases the expression of matrix metalloproteinases-1 and interleukin-6. Microgravity reduces the expression of collagen I, and the level of fibrillar collagen, which affects the mechanical properties of the intracellular matrix. Matrix metalloproteinases -1, -3, -10 demonstrated an increased activity in flight samples of 16-week-old female C57BL/6J mice (n = 8) during 15 days aboard the Space Shuttle Discovery, the STS-131 mission, compared to ground control (12.94; 2.98 and 16.85 times, respectively, P<0.05), while matrix metalloproteinases inhibitors – tissue metalloproteinase inhibitors-1, -2, and -3, demonstrated no statistically significant changes in gene expression. There were determined significant differences in the gene expression profiles in the lungs of animals of the space flight and ground control groups. The genes that revealed more than doubled expression were CTGF, MMP-2, NACM1, SPARC, SPOCK1 and TIMP-3, while the genes with the greatest decrease in expression were LAMA1, MMP-3, MMP-7, MMP-13, VCAM-1, and SELE.

Математическая модель идентификации космических аппаратов

Proposed below is a mathematical model for reception and processing of spurious (“uncontrolled” radiation) from constantly operating units of the special complex installed onboard a spacecraft. This model makes it possible to implement a new technique for identification of such radiation thus improving the capabilities of the space monitoring. At the same time creation of stand-alone radio systems solely for identification of the spacecrafts based on the proposed mathematic model would require significant expenses therefore it is worthwhile to add new identification hardware to the existing ground-based radio systems used for space flight control. Identifying features in the proposed mathematical model are the parameters of signals of the uncontrolled radiation from constantly operating units installed onboard spacecrafts that “leak” through antenna systems (master generators, heterodyne oscillators in the spacecraft radio receivers). Identification of spacecrafts by uncontrolled radiation from the receiving master generators and heterodyne oscillators involves keeping track of the behavior of oscillation parameters as well as identifying signs that distinguish the oscillations of one generator from another. Since the uncontrolled radiation from heterodyne oscillators is a harmonic oscillation, it features such parameters as amplitude, frequency and initial phase. It is impossible to use the amplitude and initial phase of the signal for identification purposes because the propagation medium strongly affects these parameters. The most informative for identification purposes is the frequency of oscillations, or rather, the behavior of the frequency changes over time. These changes are due to the frequency instability of the onboard master generators. The behavior of the frequency change depends on the characteristics of each onboard generator, which serves as a basis for identification. It should be noted that the identification process can be conditionally divided into two stages: the first stage includes validation of models and processing (evaluation) algorithms while the second stage involves classification of the results of processing (evaluation).

Spaceflight-Associated Vascular Remodeling and Gene Expression in Mouse Calvaria.

Astronauts suffer from a loss of bone mass at a rate of 1.5% per month from lower regions of the body during the course of long-duration (>30 days) spaceflight, a phenomenon that poses important risks for returning crew. Conversely, a gain in bone mass may occur in non-load bearing regions of the body as related to microgravity-induced cephalad fluid shift. Representing non-load bearing regions with mouse calvaria and leveraging the STS-131 (15-day) and BION-M1 (30-day) flights, we examined spatial and temporal calvarial vascular remodeling and gene expression related to microgravity exposure compared between spaceflight (SF) and ground control (GC) cohorts. We examined parasagittal capillary numbers and structures in calvaria from 16 to 23 week-old C57BL/6 female mice (GC, n = 4; SF, n = 5) from STS-131 and 19–20 week-old C57BL/6 male mice (GC, n = 6; SF, n = 6) from BION-M1 using a robust isolectin-IB4 vessel marker. We found that the vessel diameter reduces significantly in mice exposed to 15 days of spaceflight relative to control. Capillarization increases by 30% (SF vs. GC, p = 0.054) in SF mice compared to GC mice. The vessel numbers and diameter remain unchanged in BION-M1 mice calvarial section. We next analyzed the parietal pro-angiogenic (VEGFA) and pro-osteogenic gene (BMP-2, DMP1, RUNX2 and OCN) expression in BION-M1 mice using quantitative RT-PCR. VEGFA gene expression increased 15-fold while BMP-2 gene expression increased 11-fold in flight mice compared to GC. The linkage between vascular morphology and gene expression in the SF conditions suggests that angiogenesis may be important in the regulation of pathological bone growth in non-weight bearing regions of the body. Short-duration microgravity-mediated bone restructuring has implications in planning effective countermeasures for long-duration flights and extraterrestrial human habitation.

Formal Methods at Scale

This special issue of IEEE Security & Privacy offers some experience of how the formal methods (FM) community, working in partnership with sponsors and users, is achieving a broader use of this critical technology at increasing levels of scale. Formal methods have a rich history spanning a half-century. Mathematical proofs of the properties of programs have been sought since the early days of computing. Despite these aspirations, FMs have not broadly taken hold due to barriers of scale, usability, engineering realism, economics, available specially trained staff, and mission incentives. Indeed, for decades, FM tools and ecosystems could only operate on problems and systems of modest scale. There has, nonetheless, been a strong impetus to continue the advance of FM driven by emerging uses of computing hardware and software in critical systems, such as space and aircraft flight control, communication security, and cryptography.

Bone strength and composition in spacefaring rodents: systematic review and meta-analysis

Studying the effects of space travel on bone of experimental animals provides unique advantages, including the ability to perform post-mortem analysis and mechanical testing. To synthesize the available data to assess how much and how consistently bone strength and composition parameters are affected by spaceflight, we systematically identified studies reporting bone health in spacefaring animals from Medline, Embase, Web of Science, BIOSIS, and NASA Technical reports. Previously, we reported the effect of spaceflight on bone architecture and turnover in rodents and primates. For this study, we selected 28 articles reporting bone strength and composition in 60 rats and 60 mice from 17 space missions ranging from 7 to 33 days in duration. Whole bone mechanical indices were significantly decreased in spaceflight rodents, with the percent difference between spaceflight and ground control animals for maximum load of −15.24% [Confidence interval: −22.32, −8.17]. Bone mineral density and calcium content were significantly decreased in spaceflight rodents by −3.13% [−4.96, −1.29] and −1.75% [−2.97, −0.52] respectively. Thus, large deficits in bone architecture (6% loss in cortical area identified in a previous study) as well as changes in bone mass and tissue composition likely lead to bone strength reduction in spaceflight animals.

Integration of blockchain technology into the state order management system

The state order management system, which was reformed in 2013, despite constant modernization with endless legislative patches, continues to be a cumbersome bureaucratic monster, unable to cope with the ever-increasing volume of tasks. In the modern technically developed world, solving discrete distribution problems through protocol commissions and paper reports is an atavism like bone abacus in the space flight control center. One of the tools for the development of digital management of the state order system is the integration of a new form of monetary circulation into the state economy – by means of a centralized register based on blockchain technology. The purpose of this research is to form a model for integrating digital financial assets into the system of ensuring state needs. An integral process of such integration should be the digital blockchain algorithm, expressed in smart contracts and provided with financial exchange processes through digital financial assets (digital ruble in the proposed case). The way proposed by the author of the study for the introduction of a system of centralized registers supporting the financial turnover of the digital ruble into the domestic financial infrastructure is a direct embodiment of the state's policy on digitalization of state processes. The paper reveals shortcomings of the existing domestic legislation regarding the regulation of the management processes of the state order system. The concept of "digital financial assets", "digital ruble" is disclosed. An effective method is proposed to prevent the formation of economic risk factors through the corruption component in the execution of government contracts.

Peer review declaration

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing. • Type of peer review: Open • Conference submission management system: s (one page of text) and Papers in English offered for inclusion in the Moscow FAPM-2019 Program should be sent to the Local Organizing Committee. • • The format of files of abstracts and papers is *.docx and *.doc (you also should send the copy in PDF format). An article should be formed as one file and should include: • • 1. A title; • • 2. Information about authors; • • 3. Key words; • • 4. A brief annotation; • • 5. Text of paper; • • 6. A list of references; • • 7. Illustrations and tables should be numbered and titled and be included into the text of paper. All papers and abstracts should be formed due to the rules which you can find on the Moscow FAPM-2019 web-site. All enquiries concerning length of abstracts, papers, registration, accommodation, etc. should be sent to the Organizing Committee preferably by e-mail to FAPM2019@mail.ru The articles should be thoroughly revised and put into shape in according to requirements. The Proceedings will generally revised, therefore, the Organizing Committee keeps the rights for itself to use the special review of any article. In the case reviewers will be specialists of Leading Universities of Russia or aboard. • Number of submissions received: 112 • Number of submissions sent for review: 84 • Number of submissions accepted: 38 • Acceptance Rate (Number of Submissions Accepted / Number of Submissions Received X 100): 45 • Average number of reviews per paper: 2 • Total number of reviewers involved: 18 • Any additional info on review process: First, we send an invitation to take part in our conference to as many potential participants as possible from Russian and foreign scientific and educational institutions. • • We send the resulting abstracts to one of the following sections: • • • Theoretical mechanics • Celestial Mechanics • Mathematical modeling of mechanical systems, stability, traffic control • Hydromechanics • Aerodynamics, ballistics and space flight control • Applied mechanics, theory of oscillations • Problems of optimization, identification and reliability of mechanical and hydromechanical systems • Biomechanics, robotics, mechatronics • Theory of Mechanisms and Mechanics of Machines • Computational mathematics in mechanics • Topical issues of natural sciences • Scientific-methodical and historical questions of mechanics • • Further, the participants must make an oral presentation at the conference. Each section has 1-2 supervisors from among well-known Russian or foreign scientists, who can, after hearing the report, recommend publishing an article on this work. Works must be original and new, not previously published anywhere. Have scientific novelty and relevance. If all these conditions are met, and there is also a recommendation from the supervisor of the section, then we accept the article in order to apply. • Contact person for queries: Barkin Mikhail, Bauman Moscow State Technical University, barkin@bmstu.ru, barkin@yandex.ru

Стандартизация аппаратуры и методик медицинского контроля в пилотируемых космических полетах и вопросы телемедицины

Since April 1961, all manned space flights have been accompanied by medical control ensuring flight safety. Medical control in space flight has a technological and medical methodology that allows, at a distance from medical specialists, to make an adequate medical decision for the current situation. This work would be impossible if there were no measures taken to unify and standardize equipment and techniques. Telemedicine technologies developed on the basis of flight medical control. The origin of the word telemedicine comes from the expression «telemetric medical information», adopted in space technology. The issues of mutual development and mutual enrichment, standardization of methods and equipment of two areas of medicine, medical control in extreme situations and general telemedicine are considered in this article.

An identifier-actor-optimizer policy learning architecture for optimal control of continuous-time nonlinear systems

An intelligent solution method is proposed to achieve real-time optimal control for continuous-time nonlinear systems using a novel identifier-actor-optimizer (IAO) policy learning architecture. In this IAO-based policy learning approach, a dynamical identifier is developed to approximate the unknown part of system dynamics using deep neural networks (DNNs). Then, an indirect-method-based optimizer is proposed to generate high-quality optimal actions for system control considering both the constraints and performance index. Furthermore, a DNN-based actor is developed to approximate the obtained optimal actions and return good initial guesses to the optimizer. In this way, the traditional optimal control methods and state-of-the-art DNN techniques are combined in the IAO-based optimal policy learning method. Compared to the reinforcement learning algorithms with actor-critic architectures that suffer hard reward design and low computational efficiency, the IAO-based optimal policy learning algorithm enjoys fewer user-defined parameters, higher learning speeds, and steadier convergence properties in solving complex continuous-time optimal control problems (OCPs). Simulation results of three space flight control missions are given to substantiate the effectiveness of this IAO-based policy learning strategy and to illustrate the performance of the developed DNN-based optimal control method for continuous-time OCPs.

ПРИНЦИПЫ ПОСТРОЕНИЯ АЛГОРИТМИЧЕСКОГО ОБЕСПЕЧЕНИЯ ИНТЕЛЛЕКТУАЛИЗИРОВАННОЙ СИСТЕМЫ КОНТРОЛЯ ДЛЯ УПРАВЛЕНИЯ КОСМИЧЕСКИМ ПОЛЕТОМ

The article examines the issue of forming the principles of constructing algorithmic support for an intellectualized control system during space flight control. The features of the application of "classical" stochastic models for spacecraft (SC) are briefly analyzed. It is proposed to compensate for these shortcomings by introducing an intellectualized control system. On the basis of modern approaches, it is proposed to use digital intelligent models of spacecraft functioning on the basis of technological knowledge, which is telemetric information. An approach based on the development and integration of methods combining intelligent identification of individual components of a spacecraft using various analysis algorithms for imitating the functioning of the spacecraft as a whole is presented. The basic requirements for intelligent control systems and the tasks to be solved are formulated, taking into account the peculiarities of the space flight control process. The principle of the control technique using a digital twin created on the basis of real data of the spacecraft functioning is enlarged.

Направления интеллектуализации операций контроля, применимые для оперативного управления полетом космических аппаратов

Направления интеллектуализации операций контроля, применимые для оперативного управления полетом космических аппаратов

Transcriptomic Analysis Reveals the Effects of Microgravity on Rice Calli on Board the Chinese Spaceship Shenzhou 8

Rice calli were loaded onto the stationary and rotating platforms of a biological incubator (SIMBOX) during spaceflight and ground control experiments. The calli in the SIMBOX were fixed with RNAlater in space after a 324-h spacecraft flight, as well as on the ground at the same time point in a ground control experiment. Microgravity-responsive (MR) transcripts were identified by a comparison of the spaceflight controls (F-μg) with the 1-g ground controls (G-1g) and 1-g inflight controls (F-1g). MapMan analysis was used to classify 955 MR transcripts. These transcripts mainly belonged to the following categories: cell wall modification and metabolism, glycolysis and the tricarboxylic acid (TCA) cycle, transcription factors, protein modification and degradation, hormone metabolism and signalling, calcium regulation, receptor-like kinase activity, and transporters. Here, we focused on the effects of microgravity on the plant cell wall and discussed the relationship between the variation in the cell wall and plant cell growth under microgravity.

Electric sail space flight dynamics and controls

This paper seeks to investigate the space flight dynamics of a rotating barbell Electric Sail (E-Sail). This E-Sail contains two 6U CubeSats connected to 8 km tethers joined at a central hub. The central hub is designed to be an insulator so that each tether can have differing voltages. An electron gun positively charges each tether which interacts with the solar wind to produce acceleration. If the voltage on each tether is different, the trajectory of the system can be altered. Flapping modes and tension spikes are found during many of these maneuvers and care must be taken to mitigate the magnitude of these oscillations. Using sinusoidal voltage inputs, it is possible to control the trajectory of this two-body E-Sail and propel the system to Near-Earth-Objects or even deep space.

Effects of materials surface preparation for use in spacecraft potable water storage tanks

Maintaining a safe supply of potable water is of utmost importance when preparing for long-duration spaceflight missions, with the minimization of microbial growth being one major aspect. While biocides, such as ionic silver, historically have been used for microbial control in spaceflight, their effectiveness is sometimes limited due to surface reactions with the materials of the storage containers that reduce their concentrations below the effective range. For the Multi-Purpose Crew Vehicle, the primary wetted materials of the water storage system are stainless steel and a titanium alloy, and ionic silver has been chosen to serve as the biocide. As an attempt to understand what processes might reduce the known losses of silver, different treatment processes were attempted and samples of the wetted materials were tested, individually and together, to determine the relative loss of biocide under representative surface area-to-volume ratios. The results of testing presented here showed that the materials could be treated by a nitric acid rinse or a high-concentration silver spike to reduce the loss of silver and bacterial growth. It was also found that the minimum biocidal concentration could be maintained for over 28 days. These results have pointed to approaches that could be used to successfully maintain silver in spacecraft water systems for long-duration missions.

Changes in apoptotic microRNA and mRNA expression profiling in Caenorhabditis elegans during the Shenzhou-8 mission.

Radiation and microgravity exposure have been proven to induce abnormal apoptosis in microRNA (miRNA) and mRNA expression, but whether space conditions, including radiation and microgravity, activate miRNAs to regulate the apoptosis is undetermined. For that purpose, we investigated miRNome and mRNA expression in the ced-1 Caenorhabditis elegans mutant vs the wild-type, both of which underwent spaceflight, spaceflight 1g-centrifuge control and ground control conditions during the Shenzhou-8 mission. Results showed that no morphological changes in the worms were detected, but differential miRNA expression increased from 43 (ground control condition) to 57 and 91 in spaceflight and spaceflight control conditions, respectively. Microgravity altered miRNA expression profiling by decreasing the number and significance of differentially expressed miRNA compared with 1 g incubation during spaceflight. Alterations in the miRNAs were involved in alterations in apoptosis, neurogenesis larval development, ATP metabolism and GTPase-mediated signal transduction. Among these, 17 altered miRNAs potentially involved in apoptosis were screened and showed obviously different expression signatures between space conditions. By integrated analysis of miRNA and mRNA, miR-797 and miR-81 may be involved in apoptosis by targeting the genes ced-10 and both drp-1 and hsp-1, respectively. Compared with ground condition, space conditions regulated apoptosis though a different manner on transcription, by altering expression of seven core apoptotic genes in spaceflight condition, and eight in spaceflight control condition. Results indicate that, miRNA of Caenorhabditis elegans probably regulates apoptotic gene expression in response to space environmental stress, and shows different behavior under microgravity condition compared with 1 g condition in the presence of space radiation.

Transcriptome Analysis of Oryza sativa Calli Under Microgravity

The transcriptome of Oryza sativacalli was analyzed on board the Chinese spaceship “Shenzhou 8” to study the effects of microgravity on plant signal transduction and secondary metabolism (as one of the experiments with SIMBOX on Shenzhou 8). Calli of Oryza sativa were pre-cultured for 4 days on ground and then loaded into the stationary platform or the rotating platform of a biological incubator, called SIMBOX, to grow in space under microgravity conditions or 1g-conditions, respectively. The calli were fixed by RNAlater after grew 324 h under microgravity. After 17 days, Shenzhou 8 returned to Earth carrying SIMBOX. Oryza sativa calli were recovered, and the RNA was extracted for transcriptome analysis. After comparing 1 gspaceflight controls-inflight controls with 1 g-ground controls, 157 probe sets with different expression levels (fold change ≥2, p<0.05) were identified. When comparing spaceflight controls to 1 g-ground controls and to 1 g-inflight controls, 678 probe sets with different expression levels (fold change ≥2, p<0.05) were identified. The fact that the same 678 probe sets were identified in these two comparisons suggests that transcription was affected under microgravity conditions. MapMan analysis was used to classify 627 microgravity responsive (MR) transcripts. The MR transcripts were mainly involved in cell wall structure, the TCA cycle, primary metabolism, transcription, protein modification and degradation, hormone metabolism, calcium regulation, receptor like kinase activity and transport.

Mission Reliability, Cost and Time for Cold Standby Computing Systems with Periodic Backup

Life critical applications like space missions and flight controls require their computing systems to be equipped with some fault-tolerance mechanism to meet stringent reliability requirements by performing the intended function even in the case of element failures. Such benefit, however, cannot come without extra time as well as extra overhead and capital costs. This paper for the first time considers the modeling and evaluation of mission reliability, expected mission time and cost simultaneously for 1-out-of- <inline-formula><tex-math>$N$</tex-math></inline-formula> : G non-repairable cold standby computing systems subject to periodic backup actions. Based on the suggested numerical evaluation method, the optimal backup frequency problems are formulated and solved, providing the optimal number of backup operations during the mission to maximize the system reliability or to minimize the mission cost or time. In the case of non-identical system elements, the optimal standby element sequencing problem arises as the order in which the system elements are initiated can impact the system reliability and mission cost and time greatly; such problems are formulated and solved for the 1-out-of- <inline-formula><tex-math>$N$</tex-math></inline-formula> : G cold standby computing systems with periodic backups. Furthermore, a combined optimization problem is considered, where a combination of the element initiation sequence and backup frequency providing the best combination of mission reliability, cost, and time is found. The proposed methodology can facilitate a reliability-cost-time tradeoff study in the practical design of cold standby systems, thus assist in making the optimal decision on the system's standby and backup policy. Examples are provided for illustrating the considered problems and suggested solution methodology.