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1.
Vet Rec ; 194(5): 200, 2024 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-38427417
3.
Astrobiology ; 24(S1): S76-S106, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38498817

RESUMO

Within the first billion years of Earth's history, the planet transformed from a hot, barren, and inhospitable landscape to an environment conducive to the emergence and persistence of life. This chapter will review the state of knowledge concerning early Earth's (Hadean/Eoarchean) geochemical environment, including the origin and composition of the planet's moon, crust, oceans, atmosphere, and organic content. It will also discuss abiotic geochemical cycling of the CHONPS elements and how these species could have been converted to biologically relevant building blocks, polymers, and chemical networks. Proposed environments for abiogenesis events are also described and evaluated. An understanding of the geochemical processes under which life may have emerged can better inform our assessment of the habitability of other worlds, the potential complexity that abiotic chemistry can achieve (which has implications for putative biosignatures), and the possibility for biochemistries that are vastly different from those on Earth.


Assuntos
Planeta Terra , Planetas , Lua , Atmosfera/química , Oceanos e Mares
4.
Astrobiology ; 24(S1): S57-S75, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38498821

RESUMO

The materials that form the diverse chemicals and structures on Earth-from mountains to oceans and biological organisms-all originated in a universe dominated by hydrogen and helium. Over billions of years, the composition and structure of the galaxies and stars evolved, and the elements of life, CHONPS, were formed through nucleosynthesis in stellar cores. Climactic events such as supernovae and stellar collisions produced heavier elements and spread them throughout the cosmos, often to be incorporated into new, more metal-rich stars. Stars typically form in molecular clouds containing small amounts of dust through the collapse of a high-density core. The surrounding nebular material is then pulled into a protoplanetary disk, from which planets, moons, asteroids, and comets eventually accrete. During the accretion of planetary systems, turbulent mixing can expose matter to a variety of different thermal and radiative environments. Chemical and physical changes in planetary system materials occur before and throughout the process of accretion, though many factors such as distance from the star, impact history, and level of heating experienced combine to ultimately determine the final geophysical characteristics. In Earth's planetary system, called the Solar System, after the orbits of the planets had settled into their current configuration, large impacts became rare, and the composition of and relative positions of objects became largely fixed. Further evolution of the respective chemical and physical environments of the planets-geosphere, hydrosphere, and atmosphere-then became dependent on their local geochemistry, their atmospheric interactions with solar radiation, and smaller asteroid impacts. On Earth, the presence of land, air, and water, along with an abundance of important geophysical and geochemical phenomena, led to a habitable planet where conditions were right for life to thrive.


Assuntos
Planetas , Sistema Solar , Planeta Terra , Atmosfera/química , Planetas Menores , Evolução Planetária , Meio Ambiente Extraterreno/química
5.
Astrobiology ; 24(S1): S202-S215, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38498825

RESUMO

Planetary protection is a principle in the design of interplanetary missions that aims to prevent biological cross contamination between the target body and Earth. Planetary protection policies and procedures have worked to mitigate forward contamination (from Earth) and back contamination (to Earth) since the beginning of the space age. Today, planetary protection policy is guided by international agreements, nongovernmental advisory councils, and national space agencies. The landscape of planetary protection science and policy is changing rapidly, as new technologies, crewed missions to Mars and the Moon, and even orbital settlements are being developed. Space exploration, whether specifically targeted toward questions in astrobiology or not, must consider planetary protection concerns to minimize contamination that poses a risk to both astrobiological investigations as well as Earth's biosphere. In this chapter, we provide an introduction to and overview of the history, motivations, and implementation of planetary protection in the United States.


Assuntos
Marte , Voo Espacial , Estados Unidos , Meio Ambiente Extraterreno , Contenção de Riscos Biológicos , Planetas , Exobiologia
6.
Astrobiology ; 24(S1): S164-S185, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38498822

RESUMO

The search for life beyond Earth necessitates a rigorous and comprehensive examination of biosignatures, the types of observable imprints that life produces. These imprints and our ability to detect them with advanced instrumentation hold the key to our understanding of the presence and abundance of life in the universe. Biosignatures are the chemical or physical features associated with past or present life and may include the distribution of elements and molecules, alone or in combination, as well as changes in structural components or physical processes that would be distinct from an abiotic background. The scientific and technical strategies used to search for life on other planets include those that can be conducted in situ to planetary bodies and those that could be observed remotely. This chapter discusses numerous strategies that can be employed to look for biosignatures directly on other planetary bodies using robotic exploration including those that have been deployed to other planetary bodies, are currently being developed for flight, or will become a critical technology on future missions. Search strategies for remote observations using current and planned ground-based and space-based telescopes are also described. Evidence from spectral absorption, emission, or transmission features can be used to search for remote biosignatures and technosignatures. Improving our understanding of biosignatures, their production, transformation, and preservation on Earth can enhance our search efforts to detect life on other planets.


Assuntos
Exobiologia , Meio Ambiente Extraterreno , Planetas , Planeta Terra
7.
Astrobiology ; 24(S1): S143-S163, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38498826

RESUMO

All known life on Earth inhabits environments that maintain conditions between certain extremes of temperature, chemical composition, energy availability, and so on (Chapter 6). Life may have emerged in similar environments elsewhere in the Solar System and beyond. The ongoing search for life elsewhere mainly focuses on those environments most likely to support life, now or in the past-that is, potentially habitable environments. Discussion of habitability is necessarily based on what we know about life on Earth, as it is our only example. This chapter gives an overview of the known and presumed requirements for life on Earth and discusses how these requirements can be used to assess the potential habitability of planetary bodies across the Solar System and beyond. We first consider the chemical requirements of life and potential feedback effects that the presence of life can have on habitable conditions, and then the planetary, stellar, and temporal requirements for habitability. We then review the state of knowledge on the potential habitability of bodies across the Solar System and exoplanets, with a particular focus on Mars, Venus, Europa, and Enceladus. While reviewing the case for the potential habitability of each body, we summarize the most prominent and impactful studies that have informed the perspective on where habitable environments are likely to be found.


Assuntos
Exobiologia , Meio Ambiente Extraterreno , Meio Ambiente Extraterreno/química , Planetas , Planeta Terra , Sistema Solar
9.
Glob Chang Biol ; 30(2): e17195, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38389196

RESUMO

Scientific innovation is overturning conventional paradigms of forest, water, and energy cycle interactions. This has implications for our understanding of the principal causal pathways by which tree, forest, and vegetation cover (TFVC) influence local and global warming/cooling. Many identify surface albedo and carbon sequestration as the principal causal pathways by which TFVC affects global warming/cooling. Moving toward the outer latitudes, in particular, where snow cover is more important, surface albedo effects are perceived to overpower carbon sequestration. By raising surface albedo, deforestation is thus predicted to lead to surface cooling, while increasing forest cover is assumed to result in warming. Observational data, however, generally support the opposite conclusion, suggesting surface albedo is poorly understood. Most accept that surface temperatures are influenced by the interplay of surface albedo, incoming shortwave (SW) radiation, and the partitioning of the remaining, post-albedo, SW radiation into latent and sensible heat. However, the extent to which the avoidance of sensible heat formation is first and foremost mediated by the presence (absence) of water and TFVC is not well understood. TFVC both mediates the availability of water on the land surface and drives the potential for latent heat production (evapotranspiration, ET). While latent heat is more directly linked to local than global cooling/warming, it is driven by photosynthesis and carbon sequestration and powers additional cloud formation and top-of-cloud reflectivity, both of which drive global cooling. TFVC loss reduces water storage, precipitation recycling, and downwind rainfall potential, thus driving the reduction of both ET (latent heat) and cloud formation. By reducing latent heat, cloud formation, and precipitation, deforestation thus powers warming (sensible heat formation), which further diminishes TFVC growth (carbon sequestration). Large-scale tree and forest restoration could, therefore, contribute significantly to both global and surface temperature cooling through the principal causal pathways of carbon sequestration and cloud formation.


Assuntos
Sequestro de Carbono , Mudança Climática , Florestas , Planetas , Temperatura , Água , Temperatura Baixa , Árvores
10.
Sci Rep ; 14(1): 3691, 2024 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-38355968

RESUMO

The universe is a vast store of organic abiotic carbon that could potentially drive heterotrophy on habitable planets. Meteorites are one of the transporters of this carbon to planetary surfaces. Meteoritic material was accumulating on early Earth when life emerged and proliferated. Yet it is not known if this organic carbon from space was accessible to life. In this research, an anaerobic microbial community was grown with the CM2 carbonaceous chondrite Aguas Zarcas as the sole carbon, energy and nutrient source. Using a reversed 13C-stable isotope labelling experiment in combination with optical photothermal infrared (O-PTIR) spectroscopy of single cells, this paper demonstrates the direct transfer of carbon from meteorite into microbial biomass. This implies that meteoritic organics could have been used as a carbon source on early Earth and other habitable planets, and supports the potential for a heterotrophic metabolism in early living systems.


Assuntos
Carbono , Meteoroides , Carbono/química , Planeta Terra , Planetas , Meio Ambiente Extraterreno
11.
Am J Clin Nutr ; 119(2): 384-392, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38309827

RESUMO

BACKGROUND: The Planetary Health Diet Index (PHDI) is a novel measure adapted to quantify alignment with the dietary evidence presented by the EAT-Lancet Commission on Food, Planet, Health. OBJECTIVES: To examine how population-level health and sustainability of diet as measured by the PHDI changed from 2003 to 2018, and to assess how PHDI correlated with inadequacy for nutrients of public health concern (iron, calcium, potassium, and fiber) in the United States. METHODS: We estimated survey-weighted trends in PHDI scores and median intake of PHDI components in a nationally representative sample of 33,859 adults aged 20+ y from 8 cycles (2003-2018) of the National Health and Nutrition Examination Survey with 2 d of dietary recall data. We used the National Cancer Institute method to examine how PHDI correlated with inadequate intake of iron, calcium, potassium, and fiber. RESULTS: Out of a theoretical range of 0-140, the median PHDI value increased by 4.2 points over the study period, from 62.7 (95% confidence interval [CI]: 62.0, 63.4) points in 2003-2004 to 66.9 (66.2, 67.7) points in 2017-2018 (P-trend < 0.001), although most of this change occurred before 2011-2012 and plateaued thereafter. For adequacy components that are encouraged for consumption, nonstarchy vegetable intake significantly decreased over time, whereas whole grains, nuts and seeds, and unsaturated oils increased. For moderation components with recommended limits for consumption, poultry and egg intake increased, but red and processed meat, added sugars, saturated fats, and starchy vegetables decreased over time. Higher PHDI values were associated with a lower probability of iron, fiber, and potassium inadequacy. CONCLUSIONS: Although there have been positive changes over the past 20 y, there is substantial room for improving the health and sustainability of the United States diet. Shifting diets toward EAT-Lancet recommendations would improve nutrient adequacy for iron, fiber, and potassium. Policy action is needed to support healthier, more sustainable diets in the United States and globally.


Assuntos
Cálcio , Saúde Pública , Adulto , Humanos , Estados Unidos , Inquéritos Nutricionais , Planetas , Dieta , Nutrientes , Verduras , Ferro , Potássio , Ingestão de Energia
12.
Lancet ; 403(10428): 712, 2024 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-38401956

Assuntos
Planetas , Humanos
13.
Lancet ; 403(10426): 521-522, 2024 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-38342120
14.
Astrobiology ; 24(3): 283-299, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38377582

RESUMO

Modeling the detection of life has never been more opportune. With next-generation space telescopes, such as the currently developing Habitable Worlds Observatory (HWO) concept, we will begin to characterize rocky exoplanets potentially similar to Earth. However, few realistic planetary spectra containing surface biosignatures have been paired with direct imaging telescope instrument models. Therefore, we use a HWO instrument noise model to assess the detection of surface biosignatures affiliated with oxygenic, anoxygenic, and nonphotosynthetic extremophiles. We pair the HWO telescope model to a one-dimensional radiative transfer model to estimate the required exposure times necessary for detecting each biosignature on planets with global microbial coverage and varying atmospheric water vapor concentrations. For modeled planets with 0-50% cloud coverage, we determine pigments and the red edge could be detected within 1000 hr (100 hr) at distances within 15 pc (11 pc). However, tighter telescope inner working angles (2.5 λ/D) would allow surface biosignature detection at further distances. Anoxygenic photosynthetic biosignatures could also be more easily detectable than nonphotosynthetic pigments and the photosynthetic red edge when compared against a false positive iron oxide slope. Future life detection missions should evaluate the influence of false positives on the detection of multiple surface biosignatures.


Assuntos
Exobiologia , Meio Ambiente Extraterreno , Exobiologia/métodos , Planetas , Planeta Terra , Oxigênio
15.
PLoS One ; 19(1): e0296069, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38198440

RESUMO

BACKGROUND: The Planetary Health Diet Index (PHDI) measures adherence to the sustainable dietary guidance proposed by the EAT-Lancet Commission on Food, Planet, Health. To justify incorporating sustainable dietary guidance such as the PHDI in the US, the index needs to be compared to health-focused dietary recommendations already in use. The objectives of this study were to compare the how the Planetary Health Diet Index (PHDI), the Healthy Eating Index-2015 (HEI-2015) and Dietary Approaches to Stop Hypertension (DASH) relate to cardiometabolic risk factors. METHODS AND FINDINGS: Participants from the National Health and Nutrition Examination Survey (2015-2018) were assigned a score for each dietary index. We examined disparities in dietary quality for each index. We used linear and logistic regression to assess the association of standardized dietary index values with waist circumference, blood pressure, HDL-C, fasting plasma glucose (FPG) and triglycerides (TG). We also dichotomized the cardiometabolic indicators using the cutoffs for the Metabolic Syndrome and used logistic regression to assess the relationship of the standardized dietary index values with binary cardiometabolic risk factors. We observed diet quality disparities for populations that were Black, Hispanic, low-income, and low-education. Higher diet quality was associated with improved continuous and binary cardiometabolic risk factors, although higher PHDI was not associated with high FPG and was the only index associated with lower TG. These patterns remained consistent in sensitivity analyses. CONCLUSIONS: Sustainability-focused dietary recommendations such as the PHDI have similar cross-sectional associations with cardiometabolic risk as HEI-2015 or DASH. Health-focused dietary guidelines such as the forthcoming 2025-2030 Dietary Guidelines for Americans can consider the environmental impact of diet and still promote cardiometabolic health.


Assuntos
Doenças Cardiovasculares , Abordagens Dietéticas para Conter a Hipertensão , Humanos , Dieta Saudável , Estudos Transversais , Inquéritos Nutricionais , Planetas , Dieta , Doenças Cardiovasculares/prevenção & controle
16.
Nat Commun ; 15(1): 261, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38199986

RESUMO

Meeting global commitments to conservation, climate, and sustainable development requires consideration of synergies and tradeoffs among targets. We evaluate the spatial congruence of ecosystems providing globally high levels of nature's contributions to people, biodiversity, and areas with high development potential across several sectors. We find that conserving approximately half of global land area through protection or sustainable management could provide 90% of the current levels of ten of nature's contributions to people and meet minimum representation targets for 26,709 terrestrial vertebrate species. This finding supports recent commitments by national governments under the Global Biodiversity Framework to conserve at least 30% of global lands and waters, and proposals to conserve half of the Earth. More than one-third of areas required for conserving nature's contributions to people and species are also highly suitable for agriculture, renewable energy, oil and gas, mining, or urban expansion. This indicates potential conflicts among conservation, climate and development goals.


Assuntos
Ecossistema , Planetas , Humanos , Biodiversidade , Agricultura , Clima
18.
J Am Coll Radiol ; 21(2): 280-284, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38042232

RESUMO

The planet has a fever, and it is getting worse. Climate change manifests through mechanisms such as extreme weather, shifting disease burden, wildfires, and drought, which all have negative implications on human health. Simultaneously, the health care sector is responsible for 4.6% of global greenhouse gas emissions. As users of some of the hospital's most energy-intensive equipment, radiology departments are key stakeholders in the transition to clean energy. The authors propose a framework to guide radiology departments to advance health care sustainability. The approach outlines how a radiology department can reduce its environmental footprint through appointing a sustainability officer, forming a dedicated green team, incorporating sustainability into the departmental strategic plan, quantifying total greenhouse gas emissions, committing to education, and advocating for systemic change. By delineating a structured path, the authors hope to encourage the transition toward environmentally friendly practices in all radiology practice settings.


Assuntos
Gases de Efeito Estufa , Serviço Hospitalar de Radiologia , Radiologia , Humanos , Planetas , Tomografia Computadorizada por Raios X
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