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A crewed mission to and from Mars may include an exciting array of enabling biotechnologies that leverage inherent mass, power, and volume advantages over traditional abiotic approaches. In this perspective, we articulate the scientific and engineering goals and constraints, along with example systems, that guide the design of a surface biomanufactory. Extending past arguments for exploiting stand-alone elements of biology, we argue for an integrated biomanufacturing plant replete with modules for microbial in situ resource utilization, production, and recycling of food, pharmaceuticals, and biomaterials required for sustaining future intrepid astronauts. We also discuss aspirational technology trends in each of these target areas in the context of human and robotic exploration missions.

A long-distance manned flight, for example, to the Moon or Mars, requires an efficient and reliable system of water recovery from wastewater. The vapor compression distiller (VCD) designed for use in a near-Earth orbit and installed on the International Space Station (ISS) does not meet the requirements for deep space flights for several reasons: it has a low recovery rate (up to 85%) and low processing rate (1.5 kg/h); the compressor it uses to reduce the specific power consumption has a complex design, and peristaltic pumps used for pumping liquids have multiple flaws. These shortcomings cannot be eliminated unless the distiller is fundamentally redesigned, and thus such distiller cannot be used in long-term space missions. Therefore, alternative options must be considered. One candidate for the primary distillation for space applications is centrifugal multiple effect distiller (CMED) with a thermoelectric heat pump (THP) used as power source. This article describes the research process and the main characteristics of a three-stage and a five-stage CMED systems with THP, demonstrating their advantages. It is shown that it is possible to obtain up to 7 kg/h of distillate from urine. The effect of heat pump power on its efficiency (COP) and specific power consumption of the distiller is shown. The possibility of reducing the specific power consumption by 20–30% is shown. [ABSTRACT FROM AUTHOR]

N2 fixation is essential to the sustainability and operation of nitrogen systems but is energetically expensive. We developed a model and used sensitivity analysis to identify the impact of aerobic and anaerobic waste digestion, crop harvest index, rates of recovery of recalcitrant N, and the rate of N2 fixation in a system combining nitrogen fixation and recycling. The model indicates that the rate of N2 fixation, loss from reactors, fertilization efficiency, and crop harvest index have the largest impact on maintaining bioavailable N. N recoveries from aerobic and anaerobic digestion, as well as direct-to-soil fertilization, are not well characterized, but the case studies using this model indicate that their efficiencies are critical to N recovery. The findings of this model and its presented case studies can be used as a guide in the design of closed-loop habitats both on Earth and in space. These results reveal a clear need for continued research in the areas of N-efficient digestion, fertilization, and fixation.

The research is based on the results of air quality monitoring for the period from 2000 to 2020. The air samples have been taken onboard the International Space Station (ISS) using AK-1M samplers and delivered to Earth. The representativeness of the research results is confirmed by the long-term duration (20 years of observation) and the amount of experimental data (analysis of more than 30,000 measured concentrations of chemicals identified by gas chromatography and mass spectrometry). Statistical analysis of measured concentrations showed that the vast majority (70%) of trace contaminants detected in the ISS air have a log-normal distribution, which is confirmed by the use of the Kolmogorov-Smirnov goodness-of-fit test (p > 0.2). For the remaining 30%, the significance level of the Kolmogorov-Smirnov goodness-of-fit criterion was less than 0.2, however, the statistical distributions of these trace contaminants are characterized by unimodality, peakedness (kurtosis coefficient significantly >2) and asymmetry (skewness coefficient >1) with a shift towards lower values, which regarded as a "close to normal distribution". It has been established that the log-normal model can be accepted as a theoretical model describing the distribution of trace contaminants in the air of manned space stations. The established log-normal distribution and the ratio between the average concentrations of different averaging periods (10 : 3: 1.5 : 1) confirms the uneven nature of air pollutants in the modules and the possibility of the formation of "stagnant" zones. This is of great practical importance, which must be taken into account when establishing the air quality standards for trace contaminants and designing life support systems (ventilation and air purification) for manned space stations. • Log-normal distribution of trace contaminants in space station atmosphere. • Concentrations of trace contaminants have an extreme variability in time and space. • Total air pollution increases after docking. • Mathematical approaches to predict the level of air pollution. [ABSTRACT FROM AUTHOR]

The study of ecosystems, both natural and artificial, has historically been mediated by population dynamics theories. In this framework, quantifying population numbers and related variables (associated with metabolism or biological-environmental interactions) plays a central role in measuring and predicting system-level properties. As we move toward advanced technological engineering of cells and organisms, the possibility of bioengineering ecosystems (from the gut microbiome to wildlands) opens several questions that will require quantitative models to find answers. Here, we present a comprehensive survey of quantitative modeling approaches for managing three kinds of synthetic ecosystems, sharing the presence of engineered strains. These include test tube examples of ecosystems hosting a relatively low number of interacting species, mesoscale closed ecosystems (or ecospheres), and macro-scale, engineered ecosystems. The potential outcomes of synthetic ecosystem designs and their limits will be relevant to different disciplines, including biomedical engineering, astrobiology, space exploration and fighting climate change impacts on endangered ecosystems. We propose a space of possible ecosystems that captures this broad range of scenarios and a tentative roadmap for open problems and further exploration.

The International Space Station currently requires four annual replenishments for food supply, a practice that won't be feasible for deep space missions due to the greater distances. Based on the design of closed ecological life support systems, two waste streams were identified: urea from the crew urine, volatile fatty acids (VFAs) from a first stage of anaerobic digestion of waste. The objective of this study was to assess the ability of bacterium Cupriavidus necator to produce single cell protein on urea and VFAs. Thus, the effect of carbon sources (glucose vs VFAs) and the dilution rate on the biomass composition was determined in continuous cultures. Complete transformation of the carbon source into protein-rich biomass was achieved up to 78 % cell dry weight (CDW). For both carbon sources, the protein content increased from 55.0 %CDW to 78 %CDW with a decrease in the dilution rate. Conversely, the nucleic acid and polyhydroxyalkanoate contents decreased with the dilution rate from 8.8 %CDW to 4.8 %CDW and 9.8 %CDW to 0.6 %CDW respectively. Working at a low dilution rate seems to be a good way to maximize protein content while minimizing unwanted nucleic acids and polyhydroxyalkanoates., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Establishing a sustainable life-support system for space exploration is a formidable challenge due to the vast distances, high costs, and environmental differences from Earth. Building upon the lessons from the Biosphere 2 experiment, we introduce the novel "Ecosphere" and "Biosealed" systems, self-sustaining ecosystems within customizable, enclosed containers. These systems incorporate terrestrial ecosystems and groundwater layers, offering a potential model for transplanting Earth-like biomes to extraterrestrial environments. Over 4 years, we conducted rigorous experiments and analyses to understand the dynamics of these enclosed ecosystems. We successfully mitigated moisture deficiency, a major obstacle to plant growth, by incorporating groundwater layers. Additionally, we quantified microbial communities proliferating in specific soils, including simulated lunar and Ryugu asteroid regolith, enhance plant cultivation in space environments. Metagenomic analysis of these simulated space soils revealed diverse microbial populations and their crucial role in plant growth and ecosystem stability. Notably, we identified symbiotic relationships between plants and Cyanobacteria, enhancing oxygen production, and demonstrated the potential of LED lighting as an alternative light source for plant cultivation in sun-limited space missions. We also confirmed the survival of fruit flies within these systems, relying on plant-produced oxygen and photosynthetic bacteria. Our research provides a comprehensive framework for developing future space life-support systems. The novelty of our work lies in the unique design of our enclosed ecosystems, incorporating groundwater layers and simulated extraterrestrial soils, and the detailed analysis of microbial communities within these systems. These findings offer valuable insights into the challenges and potential solutions for establishing sustainable human habitats in space, including the importance of microbial management and potential health concerns related to microbial exposure., (© 2024. The Author(s).)

For deep space exploration, radiation effects on astronauts, and on items fundamental for life support systems, must be kept under a pre-agreed threshold to avoid detrimental outcomes. Therefore, it is fundamental to achieve a deep knowledge on the radiation spatial and temporal variability in the different mission scenarios as well as on the responses of different organisms to space-relevant radiation. In this paper, we first consider the radiation issue for space exploration from a physics point of view by giving an overview of the topics related to the spatial and temporal variability of space radiation, as well as on measurement and simulation of irradiation, then we focus on biological issues converging the attention on plants as one of the fundamental components of Bioregenerative Life Support Systems (BLSS). In fact, plants in BLSS act as regenerators of resources (i.e. oxygen production, carbon dioxide removal, water and wastes recycling) and producers of fresh food. In particular, we summarize some basic statements on plant radio-resistance deriving from recent literature and concentrate on endpoints critical for the development of Space agriculture. We finally indicate some perspective, suggesting the direction future research should follow to standardize methods and protocols for irradiation experiments moving towards studies to validate with space-relevant radiation the current knowledge. Indeed, the latter derives instead from experiments conducted with different radiation types and doses and often with not space-oriented scopes. [ABSTRACT FROM AUTHOR]

For deep space exploration, radiation effects on astronauts, and on items fundamental for life support systems, must be kept under a pre-agreed threshold to avoid detrimental outcomes. Therefore, it is fundamental to achieve a deep knowledge on the radiation spatial and temporal variability in the different mission scenarios as well as on the responses of different organisms to space-relevant radiation. In this paper, we first consider the radiation issue for space exploration from a physics point of view by giving an overview of the topics related to the spatial and temporal variability of space radiation, as well as on measurement and simulation of irradiation, then we focus on biological issues converging the attention on plants as one of the fundamental components of Bioregenerative Life Support Systems (BLSS). In fact, plants in BLSS act as regenerators of resources (i.e. oxygen production, carbon dioxide removal, water and wastes recycling) and producers of fresh food. In particular, we summarize some basic statements on plant radio-resistance deriving from recent literature and concentrate on endpoints critical for the development of Space agriculture. We finally indicate some perspective, suggesting the direction future research should follow to standardize methods and protocols for irradiation experiments moving towards studies to validate with space-relevant radiation the current knowledge. Indeed, the latter derives instead from experiments conducted with different radiation types and doses and often with not space-oriented scopes.

Here we propose the concept of an electro–microbial route to uncouple food production from photosynthesis, thereby enabling production of nutritious food in space without the need to grow plant-based crops. In the proposed process, carbon dioxide is fixed into ethanol using either chemical catalysis or microbial carbon fixation, and the ethanol created is used as a carbon source for yeast to synthesize food for human or animal consumption. The process depends upon technologies that can utilize electrical energy to fix carbon into ethanol and uses an optimized strain of the yeast Saccharomyces cerevisiae to produce high-quality, food-grade, single-cell protein using ethanol as the sole carbon source in a minimal medium. Crops performing photosynthesis require months to mature and are challenging to grow under the conditions found in space, whereas the electro–microbial process could generate significant quantities of food on demand with potentially high yields and productivities. In this paper we explore the potential to provide yeast-based protein and other nutrients relevant to human dietary needs using only ethanol, urea, phosphate, and inorganic salts as inputs. It should be noted that as well as having potential to provide nutrition in space, this novel approach to food production has many valuable terrestrial applications too. For example, by enabling food production in climatically challenged environments, the electro–microbial process could potentially turn deserts into food bowls. Similarly, surplus electricity generated from large-scale renewable power sources could be used to supplement the human food chain. [ABSTRACT FROM AUTHOR]

In the present study, we developed and validated an experimental life support system (ELSS) designed to investigate coral reef associated bacterial communities. The microcosms in the ELSS consisted of coral reef sediment, synthetic seawater, and specimens of five benthic reef species. These included two hard corals Montipora digitata and Montipora capricornis, a soft coral Sarcophyton glaucum, a zoanthid Zoanthus sp., and a sponge Chondrilla sp.. Physicochemical parameters and bacterial communities in the ELSS were similar to those observed at shallow coral reef sites. Sediment bacterial evenness and higher taxonomic composition were more similar to natural-type communities at days 29 and 34 than at day 8 after transfer to the microcosms, suggesting microbial stabilization after an initial recovery period. Biotopes were compositionally distinct but shared a number of ASVs. At day 34, sediment specific ASVs were found in hosts and visa versa. Transplantation significantly altered the bacterial community composition of M. digitata and Chondrilla sp., suggesting microbial adaptation to altered environmental conditions. Altogether, our results support the suitability of the ELSS developed in this study as a model system to investigate coral reef associated bacterial communities using multi-factorial experiments., (© 2024. The Author(s).)

The total equivalent mass of the medical support system and safety system in the astronaut's life support system is analyzed. For a prospective expedition to Mars, the life support systems (without the greenhouse) account for 27.4% of the mass and 26.4% of the volume of the habitable modules. [ABSTRACT FROM AUTHOR]

Sustainable human settlement on Mars will require in situ resource utilization (ISRU), the collection and utilization of Mars-based resources, including notably water and a substrate for food production. Plants will be fundamental components of future human missions to Mars, and the question of whether Mars soils can support plant growth is still open. Moreover, plant cultivation may suffer from the lack of in situ liquid water, which might constitute one of the biggest challenges for ISRU-based food production on Mars. Enhancing the crop yield with less water input and improving water utilization by plants are thus chief concern for sustainable ISRU food production. Hydrogels are polymers able to absorb large quantity of water and to increase soil water retention, plant establishment and growth. This work reports on the short-term assessment of plant growth in Mars soil analogs supplemented with hydrogels. Soil analogs consisted of sand and clay-rich material, with low organic matter content and alkaline pH. Soils were supplemented with 10% (w/w) potting medium and were sampled in Utah desert, in the vicinity of the Mars Desert Research Station, surrounded by soils sharing similarities in mineralogical and chemical composition to Martian soils. Height and dry biomass of spearmint (Mentha spicata) were compared under various irrigation frequencies, and seed germination of radish (Raphanus sativus) were monitored. Under limited irrigation, results indicate that the soil analogs were less capable of supporting plant growth as a comparison to potting medium. The effects of hydrogel supplementation were significant under limited irrigation and led to spearmint heights increased by 3 and 6% in clay- and sand-containing soils, respectively. Similarly, hydrogel supplementation resulted in spearmint mass increased by 110% in clay-containing soils and 78% in sand-containing soils. Additionally, while radish seeds failed to germinate in soil analogs, hydrogel supplementation allows for the germination of 27% of seeds, indicating that hydrogels might help loosening dense media with low water retention. Collectively, the results suggest that supplementation with hydrogel and plant growth substrate could help plants cope with limited irrigation and poor alkaline Mars soil analogs, and are discussed in the context of strategies for ISRU-based off-world colonization.

A crewed mission to and from Mars may include an exciting array of enabling biotechnologies that leverage inherent mass, power, and volume advantages over traditional abiotic approaches. In this perspective, we articulate the scientific and engineering goals and constraints, along with example systems, that guide the design of a surface biomanufactory. Extending past arguments for exploiting stand-alone elements of biology, we argue for an integrated biomanufacturing plant replete with modules for microbial in situ resource utilization, production, and recycling of food, pharmaceuticals, and biomaterials required for sustaining future intrepid astronauts. We also discuss aspirational technology trends in each of these target areas in the context of human and robotic exploration missions.

Sustainably producing nutrients beyond Earth is one of the biggest technical challenges for future extended human space missions. Microorganisms such as microalgae and cyanobacteria can provide astronauts with nutrients, pharmaceuticals, pure oxygen, and bio-based polymers, making them an interesting resource for constructing a circular bioregenerative life support system in space., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Phase separation in multiphase flows in space systems is a challenging task due to the absence of buoyancy. Several phase separation approaches have been presented in the last years given the important role that systems containing multiphase flows will play in future space missions. We present a review of these techniques and a trade-off analysis for their application in life support systems and, in particular, in the MELiSSA (Micro Ecological Life Support System Alternative) photosynthesis bioreactor. The candidate approaches are evaluated, both quantitatively and qualitatively, according to the defined requirements and criteria. The outcome of the trade-off analysis shows passive static and acoustic techniques as the most recommended methods to carry out phase separation in the considered bioreactor. • Review of phase separation techniques for lifesupport systems in space. • Definition of the trade-off methodology (criteria, scores). • Trade-off analysis of phase separation techniques for a MELiSSA photobioreactor. • Discussion and selection of the most appropriate techniques. [ABSTRACT FROM AUTHOR]

The problem of the optimal design of the life support systems of manned spacecraft is studied in this paper. The aim is to select components of all relevant subsystems to minimize the mass and power consumption and maximize the total technology readiness level while simultaneously satisfying the mission requirements and physical constraints. The model is developed by considering all intercommunication between the subsystems as the optimal assignment. The final problem is a mixed-integer, non-linear programming problem which is solved by a modified evolutionary optimization algorithm. A set of simulations is performed using real data, which demonstrates the efficiency of the proposed method.

Background: Provider perceptions about patient candidacy for kidney transplant (KT) are potentially significant contributors to disparities in KT. Objective: To examine nephrologists’ perceptions about factors that are important in excluding patients from KT referral, and to analyze the association between these perceptions and nephrologists’ demographic and practice characteristics. Methods: Invitations were sent to 3180 nephrologists. Among those who consented, 822 fulfilled the inclusion criteria, and 250 were randomly invited to complete a questionnaire about perceptions of factors essential in deciding not to refer patients for KT. Results: Responses from 216 participants with complete responses were analyzed. The 3 most common reasons for excluding patients were “patient’s inadequate social support” (44%), “limited understanding of the process due to patient’s inadequate education” (32%), and “patient’s age above 65” (26%). Nephrologists practicing in rural settings were more likely to consider inadequate support and limited education of patients as reasons not to refer for KT. In multivariate analysis, physicians with 2 or fewer transplant centers within 50 miles were more likely to report inadequate social support (OR: 3.15, 95% CI: 1.59–6.24) and age greater than 65 years (OR: 1.88, 95% CI: 1.01–3.49) as reasons to exclude patients from KT referral. Nephrologists whose practice included patients majority of whom had not completed high school were more likely to consider limited understanding due to inadequate education as an important reason to exclude patients from KT (OR: 3.31, 95% CI: 1.60–6.86). Conclusion: Patient’s social support, understanding, and age were the most common factors regarded by nephrologists as important in not referring patients for KT evaluation. Practice location, particularly rural setting, proximity to a transplant center, and the education level of a nephrologist’s patient population were important determinants of referral for KT.

Introduction: Basic life support is a key manoeuvre in a cardiac arrest situation that can often save a victim’s life. This study investigates the general public’s knowledge about the fundamentals of basic life support, and its association with previous training/education on basic life support and self-perception of knowledge. A secondary goal is to assess the opinion on training needs. Material and Methods: This is a cross-sectional, exploratory, and descriptive study, using a convenience sample of 655 individuals. A survey containing 21 questions was applied. A descriptive and inferential statistical analysis explored potential associations between variables. Results: The mean score for general knowledge (75.9% ± 14.2%) was statistically significantly higher (p < 0.001) than for technical knowledge (31.2% ± 29.7). Considering the overall knowledge, the mean score was 49.0% ± 20.3%, with 100 (15.3%) respondents scoring equal or higher than 70%, and only 12 (1.8%) answering all questions correctly. Less than 30% of the sample had previous training in basic life support. Discussion: The source of knowledge and time elapsed from previous training have relevant and statistically significant associations with the knowledge scores. Association of the self-perception of knowledge and the actual scores showed, in general, that participants have a correct perception of their knowledge. The knowledge scores indicate clear lack of training and knowledge among the general population. Conclusion: The results of this study reinforce the need for practical and regular basic life support training, ideally early in life and in the workplace. Participants recognize that they have residual or low basic life support knowledge and are motivated to attend training and refresher courses.

Space agencies are developing Bioregenerative Life Support Systems (BLSS) in view of upcoming long-term crewed space missions. Most of these BLSS plan to include various crops to produce different types of foods, clean water, and O 2 while capturing CO 2 from the atmosphere. However, growing these plants will require the appropriate addition of nutrients in forms that are available. As shipping fertilizers from Earth would be too costly, it will be necessary to use waste-derived nutrients. Using the example of the MELiSSA (Micro-Ecological Life Support System Alternative) loop of the European Space Agency, this paper reviews what should be considered so that nutrients recycled from waste streams could be used by plants grown in a hydroponic system. Whereas substantial research has been conducted on nitrogen and phosphorus recovery from human urine, much work remains to be done on recovering nutrients from other liquid and solid organic waste. It is essential to continue to study ways to efficiently remove sodium and chloride from urine and other organic waste to prevent the spread of these elements to the rest of the MELiSSA loop. A full nitrogen balance at habitat level will have to be achieved; on one hand, sufficient N 2 will be needed to maintain atmospheric pressure at a proper level and on the other, enough mineral nitrogen will have to be provided to the plants to ensure biomass production. From a plant nutrition point of view, we will need to evaluate whether the flux of nutrients reaching the hydroponic system will enable the production of nutrient solutions able to sustain a wide variety of crops. We will also have to assess the nutrient use efficiency of these crops and how that efficiency might be increased. Techniques and sensors will have to be developed to grow the plants, considering low levels or the total absence of gravity, the limited volume available to plant growth systems, variations in plant needs, the recycling of nutrient solutions, and eventually the ultimate disposal of waste that can no longer be used., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

The problem of the optimal design of the life support systems of manned spacecraft is studied in this paper. The aim is to select components of all relevant subsystems to minimize the mass and power consumption and maximize the total technology readiness level while simultaneously satisfying the mission requirements and physical constraints. The model is developed by considering all intercommunication between the subsystems as the optimal assignment. The final problem is a mixed-integer, non-linear programming problem which is solved by a modified evolutionary optimization algorithm. A set of simulations is performed using real data, which demonstrates the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Human space exploration and settlement will require leaps forward in life support for environmental management and healthcare. Life support systems must efficiently use nonrenewable resources packed from Earth while increasingly relying on resources available locally in space. On-demand production of components and materials (e.g., 3D printing and synthetic biology) holds promise to satisfy the evolving set of supplies necessary to outfit human missions to space. We consider here life support systems for missions planned in the 2020s, and discuss how the maker and 'do-it-yourself' (DIY) biology communities can develop rapid, on-demand manufacturing techniques and platforms to address these needs. This Opinion invites the diverse maker community into building the next generation of flight hardware for near-term space exploration. To establish a human settlement on the moon or Mars, NASA needs reliable life support systems that efficiently use nonrenewable resources packed from Earth while relying increasingly on resources available locally in space – solar energy and biological resources. Equipment for the life support system will need repair during multiyear missions. Earth will resupply when possible, but the crew will also make components in their own habitat during the mission. Both mechanical and biological ultra-low size, weight, and power (UL-SWaP) devices satisfy such technology gaps to continually maintain a habitable atmosphere. As pioneers of rapid prototyping on limited resources, the maker community could propel space travel forward by developing technologies consistent with the needs of human missions: efficient (UL-SWaP), automated, networked, and modular. [ABSTRACT FROM AUTHOR]

Purpose. Investigation of ventilation and conditioning systems for residential premises in order to ensure a healthy atmosphere and maintain a comfortable temperature in such premises. Methodology. Analytical investigation of the ventilation systems, recuperation technologies which can be applied in residential premises. Result. In this paper are considered the microclimatic features of residential premises and public premises. Constructions of air recuperators and air conditioning systems are explored. The possibility of using recuperator systems of heating and cooling for the observance of sanitary norms, determined for residential premises, is substantiated. It is noted that in the case of using ventilation and air conditioning systems in residential areas, it is important to ensure the intensity of the input and output of air at various temperatures and natural conditions. In order to ensure the temperature regime, the observance of the required humidity of air and its speed in residential premises, it is proposed to use a plate recuperator and an appropriate control system. Calculations were made to compare the amount of energy consumed and its cost for the real consumer during the heating period. Scientific novelty. An analysis of the calculations of tidal units with different types of heaters was conducted, and showed that the most effective way to heat the cold tidal air, to feed it into the room, is the electric heater in conjunction with the recuperator. Practical significance. The functional scheme, the system of ventilation and air conditioning with the use of plate recuperators are developed, which is the basis for creation of experimental complexes and laboratory installations. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is available in the text. Background: In out-of-hospital cardiac arrest, chest compression–only cardiopulmonary resuscitation (CO-CPR) has emerged as an alternative to standard CPR (S-CPR), using both chest compressions and rescue breaths. Since 2010, CPR guidelines recommend CO-CPR for both untrained bystanders and trained bystanders unwilling to perform rescue breaths. The aim of this study was to describe changes in the rate and type of CPR performed before the arrival of emergency medical services (EMS) during 3 consecutive guideline periods in correlation to 30-day survival. Methods: All bystander-witnessed out-of-hospital cardiac arrests reported to the Swedish register for cardiopulmonary resuscitation in 2000 to 2017 were included. Nonwitnessed, EMS-witnessed, and rescue breath–only CPR cases were excluded. Patients were categorized as receivers of no CPR (NO-CPR), S-CPR, or CO-CPR before EMS arrival. Guideline periods 2000 to 2005, 2006 to 2010, and 2011 to 2017 were used for comparisons over time. The primary outcome was 30-day survival. Results: A total of 30 445 patients were included. The proportions of patients receiving CPR before EMS arrival changed from 40.8% in the first time period to 58.8% in the second period, and to 68.2% in the last period. S-CPR changed from 35.4% to 44.8% to 38.1%, and CO-CPR changed from 5.4% to 14.0% to 30.1%, respectively. Thirty-day survival changed from 3.9% to 6.0% to 7.1% in the NO-CPR group, from 9.4% to 12.5% to 16.2% in the S-CPR group, and from 8.0% to 11.5% to 14.3% in the CO-CPR group. For all time periods combined, the adjusted odds ratio for 30-day survival was 2.6 (95% CI, 2.4–2.9) for S-CPR and 2.0 (95% CI, 1.8–2.3) for CO-CPR, in comparison with NO-CPR. S-CPR was superior to CO-CPR (adjusted odds ratio, 1.2; 95% CI, 1.1–1.4). Conclusions: In this nationwide study of out-of-hospital cardiac arrest during 3 periods of different CPR guidelines, there was an almost a 2-fold higher rate of CPR before EMS arrival and a concomitant 6-fold higher rate of CO-CPR over time. Any type of CPR was associated with doubled survival rates in comparison with NO-CPR. These findings support continuous endorsement of CO-CPR as an option in future CPR guidelines because it is associated with higher CPR rates and overall survival in out-of-hospital cardiac arrest. [ABSTRACT FROM AUTHOR]

Background: Provider perceptions about patient candidacy for kidney transplant (KT) are potentially significant contributors to disparities in KT. Objective: To examine nephrologists' perceptions about factors that are important in excluding patients from KT referral, and to analyze the association between these perceptions and nephrologists' demographic and practice characteristics. Methods: Invitations were sent to 3180 nephrologists. Among those who consented, 822 fulfilled the inclusion criteria, and 250 were randomly invited to complete a questionnaire about perceptions of factors essential in deciding not to refer patients for KT. Results: Responses from 216 participants with complete responses were analyzed. The 3 most common reasons for excluding patients were "patient's inadequate social support" (44%), "limited understanding of the process due to patient's inadequate education" (32%), and "patient's age above 65" (26%). Nephrologists practicing in rural settings were more likely to consider inadequate support and limited education of patients as reasons not to refer for KT. In multivariate analysis, physicians with 2 or fewer transplant centers within 50 miles were more likely to report inadequate social support (OR: 3.15, 95% CI: 1.59-6.24) and age greater than 65 years (OR: 1.88, 95% CI: 1.01-3.49) as reasons to exclude patients from KT referral. Nephrologists whose practice included patients majority of whom had not completed high school were more likely to consider limited understanding due to inadequate education as an important reason to exclude patients from KT (OR: 3.31, 95% CI: 1.60-6.86). Conclusion: Patient's social support, understanding, and age were the most common factors regarded by nephrologists as important in not referring patients for KT evaluation. Practice location, particularly rural setting, proximity to a transplant center, and the education level of a nephrologist's patient population were important determinants of referral for KT. [ABSTRACT FROM AUTHOR]

This article discloses the analysis of «feeding landscapes» and their natural ecological resources, which are the basis of life support systems of indigenous populations. We consider all following risks and changes of their traditional lifestyle. By the example of one of ethnic groups we demonstrate coping strategies and adaptations to climatic and environmental changes with due consideration of ethno-cultural specifics.

This article discloses the analysis of «feeding landscapes» and their natural ecological resources, which are the basis of life support systems of indigenous populations. We consider all following risks and changes of their traditional lifestyle. By the example of one of ethnic groups we demonstrate coping strategies and adaptations to climatic and environmental changes with due consideration of ethno-cultural specifics.

Understanding the response of plants to varied gravitational conditions is vital for developing effective food production in space bioregenerative life support systems. This study examines the impact of altered gravity conditions on the growth and morphological responses of Wolffia globosa (commonly known as "water lentils" or "duckweed"), assessing its potential as a space crop. Although an experiment testing the effect of simulated microgravity on Wolffia globosa has been previously conducted, for the first time, we investigated the effect of multiple gravity levels on the growth and morphological traits of Wolffia globosa plants. The plant responses to simulated microgravity, simulated partial gravity (Moon), and hypergravity environments were evaluated using random positioning machines and the large-diameter centrifuge. As hypothesized, we observed a slight reaction to different gravitational levels in the growth and morphological traits of Wolffia globosa. The relative growth rates (RGR) of plants subjected to simulated microgravity and partial gravity were reduced when compared to those in other gravity levels. The morphological analysis revealed differences in plant dimensions and frond length-to-width ratios under diverse gravity conditions. Our findings showed that Wolffia globosa is responsive to gravitational changes, with its growth and morphological adaptations being slightly influenced by varying gravitational environments. As for other crop species, growth was reduced by the microgravity conditions; however, RGR remained substantial at 0.33 a day. In conclusion, this study underscores the potential of Wolffia globosa as a space crop and its adaptability to diverse gravitational conditions, contributing to the development of sustainable food production and bioregenerative life support systems for future space exploration missions., (© 2024. The Author(s).)