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Planet Earth has evolved from an entirely anoxic planet with possibly a different tectonic regime to the oxygenated world with horizontal plate tectonics that we know today. For most of this time, Earth has been inhabited by a purely microbial biosphere albeit with seemingly increasing complexity over time. A rich record of this geobiological evolution over most of Earth's history provides insights into the remote detectability of microbial life under a variety of planetary conditions. We leverage Earth's geobiological record with the aim of a) illustrating the current state of knowledge and key knowledge gaps about the early Earth as a reference point in exoplanet science research; b) compiling biotic and abiotic mechanisms that controlled the evolution of the atmosphere over time; and c) reviewing current constraints on the detectability of Earth's early biosphere with state-of-the-art telescope technology. We highlight that life may have originated on a planet with a different tectonic regime and strong hydrothermal activity, and under these conditions, biogenic CH$_4$ gas was perhaps the most detectable atmospheric biosignature. Oxygenic photosynthesis, which is responsible for essentially all O$_2$ gas in the modern atmosphere, appears to have emerged concurrently with the establishment of modern plate tectonics and the continental crust, but O$_2$ accumulation to modern levels only occurred late in Earth's history, perhaps tied to the rise of land plants. Nutrient limitation in anoxic oceans, promoted by hydrothermal Fe = fluxes, may have limited biological productivity and O$_2$ production. N$_2$O is an alternative biosignature that was perhaps significant on the redox-stratified Proterozoic Earth. We conclude that the detectability of atmospheric biosignatures on Earth was not only dependent on biological evolution but also strongly controlled by the evolving tectonic context., Comment: Chapter 14 accepted for publication in the Reviews in Mineralogy and Geochemistry (RiMG) Volume 90 on "Exoplanets: Compositions, Mineralogy, and Evolution" edited by Natalie Hinkel, Keith Putirka, and Siyi Xu; 34 pages and 13 figures

Mathematical and statistical models underlie many of the world's most important fisheries management decisions. Since the 19th century, difficulty calibrating and fitting such models has been used to justify the selection of simple, stationary, single-species models to aid tactical fisheries management decisions. Whereas these justifications are reasonable, it is imperative that we quantify the value of different levels of model complexity for supporting fisheries management, especially given a changing climate, where old methodologies may no longer perform as well as in the past. Here we argue that cost-benefit analysis is an ideal lens to assess the value of model complexity in fisheries management. While some studies have reported the benefits of model complexity in fisheries, modeling costs are rarely considered. In the absence of cost data in the literature, we report, as a starting point, relative costs of single-species stock assessment and marine ecosystem models from two Australian organizations. We found that costs varied by two orders of magnitude, and that ecosystem model costs increased with model complexity. Using these costs, we walk through a hypothetical example of cost-benefit analysis. The demonstration is intended to catalyze the reporting of modeling costs and benefits.

Lightning has been suggested to play a role in triggering the occurrence of bio-ready chemical species. Future missions (PLATO, ARIEL, HWO, LIFE) and ground-based ELTs will investigate the atmospheres of potentially habitable exoplanets. We aim to study the effect of lightning on the atmospheric chemistry, how it affects false-positive and false-negative biosignatures, and if its effect would be observable on an exo-Earth and on TRAPPIST-1 planets. We use a combination of laboratory experiments, photochemical and radiative transfer modelling. With spark discharge experiments in N2-CO2-H2 gas mixtures, representing a range of possible rocky-planet atmospheres, we investigate the production of potential lightning signatures (CO, NO), possible biosignature gases (N2O, NH3, CH4), and important prebiotic precursors (HCN, Urea). Photochemical simulations are conducted for oxygen-rich and anoxic atmospheres for rocky planets in the habitable zones of the Sun and TRAPPIST-1 for a range of lightning flash rates. Synthetic spectra are calculated using SMART to study the atmosphere's reflectance, emission, and transmission spectra. Lightning enhances the spectral features of NO, NO2, and, in some cases, CO; CH4 and C2H6 may be enhanced indirectly. Lightning at a flash rate slightly higher than on modern Earth can mask the ozone features of an oxygen-rich, biotic atmosphere, making it harder to detect the biosphere. Lightning flash rates at least ten times higher than on modern Earth can mask the presence of ozone in the anoxic, abiotic atmosphere of a planet orbiting a late M dwarf, reducing the potential for a false-positive life-detection. The threshold lightning rates to eliminate oxygen and ozone false positive biosignatures on planets orbiting ultra-cool dwarfs is up to ten times higher than the modern flash rate, suggesting that lightning cannot always prevent these false-positive scenarios., Comment: Accepted for publication in Astronomy & Astrophysics. 30 pages, 22 figures (including appendix)

Bioavailable nitrogen is thought to be a requirement for the origin and sustenance of life. Before the onset of biological nitrogen fixation, abiotic pathways to fix atmospheric N2 must have been prominent to provide bioavailable nitrogen to Earth's earliest ecosystems. Lightning has been shown to produce fixed nitrogen as nitrite and nitrate in both modern atmospheres dominated by N2 and O2 and atmospheres dominated by N2 and CO2 analogous to the Archaean Earth. However, a better understanding of the isotopic fingerprints of lightning-generated fixed nitrogen is needed to assess the role of this process on the early Earth. Here, we present results from spark discharge experiments in N2-CO2 and N2-O2 gas mixtures. Our experiments suggest that lightning-driven nitrogen fixation may have been similarly efficient in the Archaean atmosphere, compared to modern times. Measurements of the isotopic ratio {\delta}15N of the discharge-produced nitrite and nitrate in solution show very low values of -6 to -15 permil after equilibration with the gas phase with a calculated endmember composition of -17 permil. These results are much lower than most {\delta}15N values documented from the sedimentary rock record, which supports the development of biological nitrogen fixation earlier than 3.2 Ga. However, some Paleoarchean records (3.7 Ga) may be consistent with lightning-derived nitrogen input, highlighting the potential role of this process for the earliest ecosystems., Comment: Accepted manuscript. Version of record published in Nature Geoscience. 29 pages (main text, methods, supplementary material), 5 figures + 4 supplementary figures

Hot Jupiters provide valuable natural laboratories for studying potential contributions of high-energy radiation to prebiotic synthesis in the atmospheres of exoplanets. In this fourth paper of the MOVES (Multiwavelength Observations of an eVaporating Exoplanet and its Star) programme, we study the effect of different types of high-energy radiation on the production of organic and prebiotic molecules in the atmosphere of the hot Jupiter HD 189733b. Our model combines X-ray and UV observations from the MOVES programme and 3D climate simulations from the 3D Met Office Unified Model to simulate the atmospheric composition and kinetic chemistry with the STAND2019 network. Also, the effects of galactic cosmic rays and stellar energetic particles are included. We find that the differences in the radiation field between the irradiated dayside and the shadowed nightside lead to stronger changes in the chemical abundances than the variability of the host star's XUV emission. We identify ammonium (NH4+) and oxonium (H3O+) as fingerprint ions for the ionization of the atmosphere by both galactic cosmic rays and stellar particles. All considered types of high-energy radiation have an enhancing effect on the abundance of key organic molecules such as hydrogen cyanide (HCN), formaldehyde (CH2O), and ethylene (C2H4). The latter two are intermediates in the production pathway of the amino acid glycine (C2H5NO2) and abundant enough to be potentially detectable by JWST., Comment: 15 pages, 11 figures, 4 tables

Adolescents experiencing the death of a parent face additional challenges in navigating the physical, mental, emotional, and social adjustment associated with adolescent development. This review explores the impact of parental death on adolescent development and offers empirical support for counseling interventions. Factors addressed include developmental issues, grief, interventions, implications for research, and suggestions for school counselors and educators.

Open classroom systems frequently use peer tutoring techniques as a means of individualizing instruction. This study investigated the effects of three variables on tutor and tutee performance: (1) the achievement level of the tutor; (2) brief tutor training in reinforcement and corrective feedback procedures; and (3) tutor expectancy about tutee performance. One hundred and twelve first graders were randomly selected to serve as tutees. Results indicated that both tutors and tutees learned a significant number of words. This positive effect was more pronounced for low achievers than for high achievers. Training of tutors significantly increased the pretest to posttest gains for both tutors and tutees. Peer tutoring guidelines that can be generated from this research include: (1) all children in a class, regardless of achievement level, should be selected to serve in the tutoring role; (2) brief tutor training in basic reinforcement and corrective feedback procedures is essential to an effective peer-tutoring program; and (3) expectancies about tutees' performance may result in less biased teaching behavior by peer tutors than by adult tutors. (SK)

This study provided a review of literature related to peer tutoring and investigated the effects of three variables on peer tutor and peer tutee performance. The variables were (1) the achievement level of the tutor, (2) brief tutor training in reinforcement and corrective feedback procedures, and (3) tutor expectancy about tutee performance. A total of 112 high and low achieving second graders in a Follow Through program were selected as tutors. Half of these tutors were randomly selected to receive two half-hour training sessions. The training was conducted in a small group setting and emphasized two reinforcement and feedback procedures: (1) responding to a correct answer with a positive comment, and (2) responding to an incorrect answer or no answer by providing the correct answer and giving the tutee a chance to say the correct answer. A group of 112 first graders was randomly selected to serve as tutees. Instructions to tutors prior to the tutoring session contained either high or low expectancies about the tutees' academic performance. Both tutors and tutees were pre- and posttested on 30 sight word flash cards, with which the children worked during the tutoring session. Results showed that both tutors and tutees learned a significant number of words. Tutors' achievement level was not a significant factor, as measured by words learned, but tutees tutored by trained tutors performed better than tutees tutored by untrained tutors. Tutor expectancies did not affect tutee performance on the posttest. (Author/BRT)

Fixed nitrogen is an essential nutrient for eukaryotes. As N2 fixation and assimilation of nitrate are catalyzed by metalloenzymes, it has been hypothesized that in Mesoproterozoic oceans nitrate was limited in offshore environments by low trace metal concentrations and high rates of denitrification in anoxic and episodically euxinic deep water masses, restricting eukaryotes to near-shore environments and limiting their evolutionary innovation. To date this hypothesis has only been tested in the Belt Supergroup (∼1.4 Ga), with results that support an onshore-offshore nitrate gradient as a potential control on eukaryote ecology. Here we present bulk nitrogen and organic carbon isotopic data from non-isochronous cross-basinal facies across the Bangemall (∼1.5 Ga) and the Roper (∼1.4–1.5 Ga) basins to better understand the extent and variability of onshore-offshore nitrogen isotope gradients in the Mesoproterozoic. Both basins show an average ∼1-2‰ enrichment in δ-15N(sub bulk) from deep to shallow facies, with a maximum range from ~1‰ offshore to +7.5‰ onshore. Unlike the Belt basin, the Bangemall and Roper basins show some offshore δ-15N(sub bulk) values that are enriched beyond the isotopic range associated with biological N2 fixation alone. This suggests a mixture of aerobic and anaerobic metabolisms offshore. In shallow waters, where δ-15N(sub bulk) enrichment peaks, an aerobic nitrogen cycle was evidently operating. Even though isotopic signatures of aerobic nitrogen cycling are seen in all parts of the Bangemall and Roper basins, our data are consistent with a lateral gradient in nitrate availability within the photic zone, with higher concentrations in near-shore environments than offshore. The variability in δ-15N(sub bulk) values in each depositional environment and the consistently low δ-15N(sub bulk) values from Mesoproterozoic units compared to the Paleoproterozoic and Neoproterozoic suggest that nitrate concentrations in the global ocean were likely low. This trend is now seen in all three Mesoproterozoic basins so far examined, and contrasts with the Paleoproterozoic and Neoproterozoic where nearly all δ-15N(sub bulk) data plot above the N2 fixation window. Thus, we propose that the Mesoproterozoic ocean was characterized by a nitrate minimum, with the lowest concentrations in offshore environments. This inference is consistent with a Mesoproterozoic O2 decline following a temporary Paleoproterozoic O2 peak, and it further supports the idea that nitrate limitation offshore may have contributed to the restriction of photosynthetic eukaryotes to near-shore environments, delaying their rise to ecological dominance until the Neoproterozoic Era.

Nitrogen is an essential nutrient for all life on Earth and possibly elsewhere. Burial of nitrogen bound to organic matter constitutes the major flux of nitrogen into sediments today, which has led to the inference that nitrogen enrichments in sedimentary rocks may be a biosignature. However, abiotic processes such as lightning or volcanism can fix atmospheric N2 and contribute to sedimentary nitrogen burial in the absence of life. It is therefore uncertain whether observed nitrogen enrichments of up to 430 ppm in Paleoarchean metasedimentary biotite grains are indeed biogenic. This study seeks to address that problem with a numerical model. The NH4(+) concentration of an abiotic ocean is modeled as a function of source fluxes, pH-dependent NH3 volatilization, and equilibrated adsorption of NH4(+) onto clay particles. The results suggest that the observed nitrogen concentrations in Paleoarchean biotite can only be reconciled with purely abiotic processes if the ocean was more acidic (pH <6) and/or if the source fluxes from lightning and volcanism were at least an order of magnitude higher (≥10(exp 12) mol/yr) than previously thought. The bulk of the nitrogen is thus most likely of biological origin. While this does not necessitate a particular metabolism such as biological N2 fixation, the data provide evidence of nitrogen utilization back to 3.8 Gyr. Nitrogen abundances could thus provide useful information in extraterrestrial missions.

Astrobiology is the science that seeks to understand the story of life in our universe. Astrobiology includes investigation of the conditions that are necessary for life to emerge and flourish, the origin of life, the ways that life has evolved and adapted to the wide range of environmental conditions here on Earth, the search for life beyond Earth, the habitability of extraterrestrial environments, and consideration of the future of life here on Earth and elsewhere. It therefore requires knowledge of physics, chemistry, biology, and many more specialized scientific areas including astronomy, geology, planetary science, microbiology, atmospheric science, and oceanography. However, astrobiology is more than just a collection of different disciplines. In seeking to understand the full story of life in the Universe in a holistic way, astrobiology asks questions that transcend all these individual scientific subjects. Astrobiological research potentially has much broader consequences than simply scientific discovery, as it includes questions that have been of great interest to human beings for millennia (e.g., are we alone?) and raises issues that could affect the way the human race views and conducts itself as a species (e.g., what are our ethical responsibilities to any life discovered beyond Earth?).

Investigated the relationship between identity and moral reasoning in high school and college students. Scores on a new measure of moral reasoning, the Ethic of Care Interview (ECI), were found to be significantly related to age, ego identity, and scores on Kohlberg's Moral Judgment Interview. The relationship between identity and ECI scores was significantly stronger for women than men. (MDM)

This paper describes the development of an oral language skills assessment instrument, called the Children's Language Assessment-Situational Tasks (CLA-ST), and its utilization in both formative and summative evaluation of the Tucson Early Education Model (TEEM) in Project Follow Through. First and third graders in Follow Through classrooms implementing TEEM and non-Follow Through comparison counterparts in a Southeastern community served as subjects. Language samples were collected in the fall and in the following spring in sessions designed to elicit language from the children. Pretest and posttest data were independent. Tape recordings made of each session were transcribed and coded for 11 language variables. A 2-factor analysis of variance was done with treatment (TEEM or comparison) and trials (pretest and posttest) as factors. Results indicate that primary children in the TEEM classrooms demonstrate superior language performance on many dimensions of language development. The paper concludes with a discussion of the utility of this kind of evaluation procedure to supplant traditional paper-and-pencil strategies. (Author/SB)

The Children's Language Assessment-Situational Tasks (CLA-ST) was developed to collect language samples within a normally operating classroom. The language is taken on a cassette tape recorder, which is placed at the foot of a small table. At this table, in a committee setting, four children are engaged with a teacher in an activity similar to those they encounter daily. The CLA-ST is broken into three segments: the first, with their own classroom teacher, utilizes a "mystery bag" containing 27 common household objects (15 minutes); the second, with a new adult (a staff research assistant), uses a set of eight picture cards that have no set solution (15 minutes); in the third, the children are left alone (five minutes), with the tape recorder running, while the adult excuses herself briefly. These three segments are intended to get different perspectives on children's language development. The first should resemble very closely children's typical use of language in the classroom. The second segment assesses whether their language style is modified in the presence of an unfamiliar adult. The third segment seeks to simulate other studies of natural language, and the children are left alone with the cards and the tape recorder running. The tapes are returned to the Arizona Center for transcription and analysis. The information is broken down into free flow format which identifies teacher and child output. These are then submitted to an analysis for basic language dimensions. (Author/DEP)