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The Earth is a powerful organic chemist, transforming vast quantities of carbon through complex processes, leading to diverse suites of products that include the fossil fuels upon which modern societies depend. When exploring how the Earth operates as an organic chemist, it is tempting to turn to how organic reactions are traditionally studied in chemistry labs. While highly informative, especially in terms of insights gained into reaction mechanisms, this approach can also be a source of frustration, as many of the reactants and conditions employed in chemistry labs have few or no parallels to geologic processes. The primary goal of this chapter is to provide examples of predicting thermodynamic influences and using the predictions to design experiments that reveal the mechanisms of how reactions occur at the elevated temperatures and pressures encountered in the Earth. This work is ongoing, and we hope this chapter will inspire numerous and diverse experimental and theoretical advances in hydrothermal organic geochemistry.
Herbicides have been a primary means of managing undesirable brush on grazing lands across southwestern United States for decades. Continued encroachment of honey mesquite and huisache on grazing lands warrants evaluation of treatment life and economics of current and experimental treatments. Treatment life is defined as the time between treatment application and when canopy cover of undesirable brush returns to a competitive level with native forage grasses (i.e. 25% canopy cover for mesquite and 30% canopy cover for huisache). Treatment life of industry standard herbicides was compared to aminocyclopyrachlor plus triclopyr amine (ACP+T) from ten broadcast-applied honey mesquite and five broadcast-applied huisache trials established from 2007 through 2013 across Texas. On average, the treatment life of industry standard treatments (IST) for huisache was 3 years. In comparison, huisache canopy cover was only 2.5% in ACP+T treated plots 3 years after treatment. The average treatment life of industry standard honey mesquite treatments was 8.6 years, while ACP+T treated plots had just 2% mesquite canopy cover at that time. Improved treatment life of ACP+T treatments compared to IST was due to higher mortality resulting in more consistent brush canopy reduction. The net present values of ACP+T and IST, for both huisache and mesquite, were similar until the treatment life of the IST application was reached (3 years for huisache and 8.6 years for honey mesquite). At that point, net present values of the programs diverged as a result of brush competition with desirable forage grasses and additional input costs associated with theoretical follow-up IST necessary to maintain optimum livestock forage production. The ACP+T treatments did not warrant a sequential application over the 12-year analysis for huisache or 20-year analysis for honey mesquite that this research covered. These results indicate ACP+T provides cost-effective, long-term control of honey mesquite and huisache.
A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs (Babakotia radofilai, Palaeopropithecus kelyus, Pachylemur sp., and Archaeolemur edwardsi), carnivores (Cryptoprocta spelea), the aardvark-like Plesiorycteropus sp., and giant ground cuckoos (Coua). Many of these represent considerable range extensions. Extant species that were extirpated from the region (e.g., Prolemur simus) are also present. Calibrated radiocarbon ages for 10 bones from extinct primates span the last three millennia. The largely undisturbed taphonomy of bone deposits supports the interpretation that many specimens fell in from a rock ledge above the entrance. Some primates and other mammals may have been prey items of avian predators, but human predation is also evident. Strontium isotope ratios (87Sr/86Sr) suggest that fossils were local to the area. Pottery sherds and bones of extinct and extant vertebrates with cut and chop marks indicate human activity in previous centuries. Scarcity of charcoal and human artifacts suggests only occasional visitation to the site by humans. The fossil assemblage from this site is unusual in that, while it contains many sloth lemurs, it lacks ratites, hippopotami, and crocodiles typical of nearly all other Holocene subfossil sites on Madagascar.
The Great Orme Bronze Age copper mine in Wales is one of Europe's largest, although its size has been attributed to a small-scale, seasonal labour force working for nearly a millennium. Here, the authors report the results of interdisciplinary research that provides evidence that Great Orme was the focus of Britain's first mining boom, c. 1600–1400 BC, probably involving a full-time mining community and the wide distribution of metalwork from Brittany to Sweden. This new interpretation suggests greater integration than previously suspected of Great Orme metal into the European Bronze Age trade/exchange networks, as well as more complex local and regional socio-economic interactions.
The effort to develop metallic alloys with increased structural strength and improved radiation performance has focused on the incorporation of either solute elements or microstructural inhomogeneities to mitigate damage. The recent discovery and development of single-phase concentrated solid-solution alloys (SP-CSAs) has prompted fundamental questions that challenge established theories and models currently applicable to conventional alloys. The current understanding of electronic and atomic effects, defect evolution, and microstructure progression suggests that radiation energy dissipates in SP-CSAs at different interaction strengths via energy carriers (electrons, phonons, and magnons). Modification of electronic- and atomic-level heterogeneities and tailoring of atomic transport processes can be realized through tuning of the chemical complexity of SP-CSAs by the selection of appropriate elements and their concentrations. Fundamental understanding of controlling energy dissipation via site-to-site chemical complexity reveals new design principles for predictive discovery and guided synthesis of new alloys with targeted functionalities, including radiation tolerance.
Application timing and environmental factors reportedly influence the efficacy of auxinic herbicides. In resistance-prone weed species such as Palmer amaranth (Amaranthus palmeri S. Watson), efficacy of auxinic herbicides recently adopted for use in resistant crops is of utmost importance to reduce selection pressure for herbicide resistance traits. Growth chamber experiments were conducted comparing the interaction of different environmental effects with application time to determine the influence of these factors on visible phytotoxicity and hydrogen peroxide (H2O2) formation in Amaranthus palmeri. Temperature displayed a high degree of influence on 2,4-D and dicamba efficacy in general, with applications at the low temperature treatment (31/20°C day/night) resulting in an increase in phytotoxicity, respectively, compared to high temperature treatments (41/30°C day/night). Application time across temperature treatments significantly affected 2,4-D-induced phytotoxicity, resulting in a ≥ 30% increase across rates with treatments at 4:00 pm compared to 8:00 am. Temperature differential had a significant influence on dicamba efficacy based on visible phytotoxicity data, with a ≥ 46% increase with high (37/20°C day/night) compared to low differential (41/30°C day/night). Concentration of H2O2 in herbicide treated plants was 34% higher under a high temperature differential compared to the low differential. Humidity treatments and application time interactions displayed undetected or inconsistent effects on visible phytotoxicity and H2O2 production. Overall, temperature-related influences seem to hold the largest environmental effect on auxinic herbicides within conditions evaluated in this study. Leaf concentration of H2O2 appears to be generally correlated with phytotoxicity, providing a potentially useful tool in determining efficacy of auxinic herbicides in field settings.
Microcredit – joint-liability loans to the poorest of the poor – has been touted as a powerful approach for combatting global poverty, but sustainability varies dramatically across banks. Efforts to improve the sustainability of microcredit have assumed defaults are caused by free-riding. Here, we point out that the response of other group members to delinquent groupmates also plays an important role in defaults. Even in the absence of any free-rider problem, some people will be unable to make their payments due to bad luck. It is other group members’ unwillingness to pitch in extra – due to, among other things, not wanting to have less than other group members – that leads to default. To support this argument, we utilize the Ultimatum Game (UG), a standard paradigm from behavioral economics for measuring one's aversion to inequitable outcomes. First, we show that country-level variation in microloan default rates is strongly correlated (overall r = 0.81) with country-level UG rejection rates, but not free-riding measures. We then introduce a laboratory model ‘Microloan Game’ and present evidence that defaults arise from inequity-averse individuals refusing to make up the difference when others fail to pay their fair share. This perspective suggests a suite of new approaches for combatting defaults that leverage findings on reducing UG rejections.
Terrorist attacks have increased globally since the late 1990s with clear evidence of psychological distress across both adults and children and young people (CYP). After the Manchester Arena terrorist attack, the Resilience Hub was established to identify people in need of psychological and psychosocial support.
To examine the severity of symptoms and impact of the programme.
The hub offers outreach, screening, clinical telephone triage and facilitation to access evidenced treatments. People were screened for trauma, depression, generalised anxiety and functioning who registered at 3, 6 and 9 months post-incident. Baseline scores were compared between screening groups (first screen at 3, 6 or 9 months) in each cohort (adult, CYP), and within groups to compare scores at 9 months.
There were significant differences in adults' baseline scores across screening groups on trauma, depression, anxiety and functioning. There were significant differences in the baseline scores of CYP across screening groups on trauma, depression, generalised anxiety and separation anxiety. Paired samples t-tests demonstrated significant differences between baseline and follow-up scores on all measures for adults in the 3-month screening group, and only depression and functioning measures for adults in the 6-month screening group. Data about CYP in the 3-month screening group, demonstrated significant differences between baseline and follow-up scores on trauma, generalised anxiety and separation anxiety.
These findings suggest people who register earlier are less symptomatic and demonstrate greater improvement across a range of psychological measures. Further longitudinal research is necessary to understand changes over time.
Identifying risk factors of individuals in a clinical-high-risk state for psychosis are vital to prevention and early intervention efforts. Among prodromal abnormalities, cognitive functioning has shown intermediate levels of impairment in CHR relative to first-episode psychosis and healthy controls, highlighting a potential role as a risk factor for transition to psychosis and other negative clinical outcomes. The current study used the AX-CPT, a brief 15-min computerized task, to determine whether cognitive control impairments in CHR at baseline could predict clinical status at 12-month follow-up.
Baseline AX-CPT data were obtained from 117 CHR individuals participating in two studies, the Early Detection, Intervention, and Prevention of Psychosis Program (EDIPPP) and the Understanding Early Psychosis Programs (EP) and used to predict clinical status at 12-month follow-up. At 12 months, 19 individuals converted to a first episode of psychosis (CHR-C), 52 remitted (CHR-R), and 46 had persistent sub-threshold symptoms (CHR-P). Binary logistic regression and multinomial logistic regression were used to test prediction models.
Baseline AX-CPT performance (d-prime context) was less impaired in CHR-R compared to CHR-P and CHR-C patient groups. AX-CPT predictive validity was robust (0.723) for discriminating converters v. non-converters, and even greater (0.771) when predicting CHR three subgroups.
These longitudinal outcome data indicate that cognitive control deficits as measured by AX-CPT d-prime context are a strong predictor of clinical outcome in CHR individuals. The AX-CPT is brief, easily implemented and cost-effective measure that may be valuable for large-scale prediction efforts.
Foodborne salmonellosis causes approximately 1 million illnesses annually in the United States. In the summer of 2017, we investigated four multistate outbreaks of Salmonella infections associated with Maradol papayas imported from four Mexican farms. PulseNet initially identified a cluster of Salmonella Kiambu infections in June 2017, and early interviews identified papayas as an exposure of interest. Investigators from Maryland, Virginia and Food and Drug Administration (FDA) collected papayas for testing. Several strains of Salmonella were isolated from papayas sourced from Mexican Farm A, including Salmonella Agona, Gaminara, Kiambu, Thompson and Senftenberg. Traceback from two points of service associated with illness sub-clusters in two states identified Farm A as a common source of papayas, and three voluntary recalls of Farm A papayas were issued. FDA sampling isolated four additional Salmonella strains from papayas sourced from Mexican Farms B, C and D. In total, four outbreaks were identified, resulting in 244 cases with illness onset dates from 20 December 2016 to 20 September 2017. The sampling of papayas and the collaborative work of investigative partners were instrumental in identifying the source of these outbreaks and preventing additional illnesses. Evaluating epidemiological, laboratory and traceback evidence together during investigations is critical to solving and stopping outbreaks.
This volume has achieved a large coverage of the experimentally well-studied areas of the temperate and subtropical coasts of the world (see Figure 1.1) – venturing into the tropics in some regions (Chapter 14, South-East Asia) and including mangroves (Chapter 17). Coral reef systems have not been considered. Much of the emphasis has been on rocky habitats as this is where the majority of experimental work on interactions has been done (but see Chapter 6). As well as reviewing regions where there has been a long history of experimental research (e.g., Chapters 2–4, 6, 10, 11, 13, 15, 16), areas of emerging experimental research in the last twenty-five years (e.g., Chapter 8, western Mediterranean; Chapter 12, south-east Pacific) and understudied regions (e.g., Chapter 7, Argentina; Chapter 14, South-East Asia) have also been included, allowing more comprehensive insights into the processes important for shaping these communities. In this short synthesis chapter, we first consider the main processes determining patterns covered by the previous chapters. We then consider major human impacts in these regions. Finally, we identify gaps in knowledge and make some suggestions for the way forward. We make the case for combining phylogeographic studies with macro-ecology and biogeography, coupled with well-designed hypothesis testing experiments, to better understand processes generating patterns on micro-evolutionary (hundreds to thousands of years) and ecological (up to hundreds of years) time scales.
Prior research has shown that person-level characteristics (e.g., temperament, personality) correlate and interact with social-contextual factors (e.g., parent–child relationship quality, antisocial peer affiliation) to predict adolescent substance use, but less research has examined similar processes for adult substance use problems. We addressed this gap by testing for personality × romantic partner context interplay in relation to symptoms of alcohol use disorder (AUD) at ages 24 and 29. Participants were twins in the longitudinal Minnesota Twin Family Study (N = 2,769; 52% female). Results support the corresponsive principle of personality in that we found that key personality traits in late adolescence (low constraint, negative emotionality) predicted subsequent “selection” into key social contexts in early adulthood (poorer quality romantic relationships and greater romantic partner alcohol use), which subsequently reinforced those traits and associated outcomes (including correlated AUD symptoms) through late young adulthood. There were few meaningful gender differences in these associations. There was also no support for the personality × romantic partner context interaction as a significant predictor of AUD symptoms at ages 24 or 29. Taken together with prior studies, these results suggest that such interactions may be less relevant to the development of young adult AUD compared to adolescent substance use problems.
We describe the design and deployment of GREENBURST, a commensal Fast Radio Burst (FRB) search system at the Green Bank Telescope. GREENBURST uses the dedicated L-band receiver tap to search over the 960–1 920 MHz frequency range for pulses with dispersion measures out to
. Due to its unique design, GREENBURST is capable of conducting searches for FRBs when the L-band receiver is not being used for scheduled observing. This makes it a sensitive single pixel detector capable of reaching deeper in the radio sky. While single pulses from Galactic pulsars and rotating radio transients will be detectable in our observations, and will form part of the database we archive, the primary goal is to detect and study FRBs. Based on recent determinations of the all-sky rate, we predict that the system will detect approximately one FRB for every 2–3 months of continuous operation. The high sensitivity of GREENBURST means that it will also be able to probe the slope of the FRB fluence distribution, which is currently uncertain in this observing band.
Recent years have seen an exponential increase in the variety of healthcare data captured across numerous sources. However, mechanisms to leverage these data sources to support scientific investigation have remained limited. In 2013 the Pediatric Heart Network (PHN), funded by the National Heart, Lung, and Blood Institute, developed the Integrated CARdiac Data and Outcomes (iCARD) Collaborative with the goals of leveraging available data sources to aid in efficiently planning and conducting PHN studies; supporting integration of PHN data with other sources to foster novel research otherwise not possible; and mentoring young investigators in these areas. This review describes lessons learned through the development of iCARD, initial efforts and scientific output, challenges, and future directions. This information can aid in the use and optimisation of data integration methodologies across other research networks and organisations.
A resurgence in work requirements for safety-net programs, including the Supplemental Nutrition Assistance Program (SNAP), has marked the early years of the Trump administration. Some lawmakers at both the federal and state level have moved to revive and expand SNAP’s work requirements, despite evidence that such work requirements do little to increase self-sufficiency or improve long-term economic outcomes among those living in poverty. This chapter takes up the issue of work requirements in the context of rural communities, where the need for safety-net programs and food system supports is acute. We begin with a brief overview of SNAP and examine the recent push to make SNAP work requirements more strict. We then turn to an overview of the need and current state of use of the social safety net in rural America. If work requirements are to be effective – and, indeed, appropriate – work opportunities must be available. We, therefore, consider employment data and information on safety-net use across the rural-urban axis. Finally, we present a case study about the results of relatively early efforts to impose work requirements on SNAP receipt in Maine.
The YBJ equation (Young & Ben Jelloul, J. Marine Res., vol. 55, 1997, pp. 735–766) provides a phase-averaged description of the propagation of near-inertial waves (NIWs) through a geostrophic flow. YBJ is obtained via an asymptotic expansion based on the limit
is the Burger number of the NIWs. Here we develop an improved version, the YBJ+ equation. In common with an earlier improvement proposed by Thomas, Smith & Bühler (J. Fluid Mech., vol. 817, 2017, pp. 406–438), YBJ+ has a dispersion relation that is second-order accurate in
. (YBJ is first-order accurate.) Thus both improvements have the same formal justification. But the dispersion relation of YBJ+ is a Padé approximant to the exact dispersion relation and with
of order unity this is significantly more accurate than the power-series approximation of Thomas et al. (2017). Moreover, in the limit of high horizontal wavenumber
, the wave frequency of YBJ+ asymptotes to twice the inertial frequency
. This enables solution of YBJ+ with explicit time-stepping schemes using a time step determined by stable integration of oscillations with frequency
. Other phase-averaged equations have dispersion relations with frequency increasing as
(Thomas et al. 2017): in these cases stable integration with an explicit scheme becomes impractical with increasing horizontal resolution. The YBJ+ equation is tested by comparing its numerical solutions with those of the Boussinesq and YBJ equations. In virtually all cases, YBJ+ is more accurate than YBJ. The error, however, does not go rapidly to zero as the Burger number characterizing the initial condition is reduced: advection and refraction by geostrophic eddies reduces in the initial length scale of NIWs so that
increases with time. This increase, if unchecked, would destroy the approximation. We show, however, that dispersion limits the damage by confining most of the wave energy to low
. In other words, advection and refraction by geostrophic flows does not result in a strong transfer of initially near-inertial energy out of the near-inertial frequency band.