We explored the site context of a late Holocene shell midden on the coast of Los Vilos in north-central Chile (31°51′ S, South America) to better understand the spatial organization of short-term, small-sized hunter-gatherer campsites. The Dunas de Agua Amarilla (LV 007) site comprises 14 separate surf clam refuse deposits. Extensive stratigraphic excavations of the shell middens and the areas free of residue allowed interpretation of potential activity areas bounded by hearths, the shell middens, and a possible dwelling space. Late Holocene campsites in the area correspond to brief occupational events framed within littoral residential mobility, in which predictable coastal resources became a staple for groups residing and circulating over long periods in the area. Data on shell midden composition and the spatial distribution of site features shed light on the organizational dynamics of dwelling and activity spaces of coastal hunter-gatherers of the South Pacific.

The Neotoma Paleoecology Database is a community-curated data resource that supports interdisciplinary global change research by enabling broad-scale studies of taxon and community diversity, distributions, and dynamics during the large environmental changes of the past. By consolidating many kinds of data into a common repository, Neotoma lowers costs of paleodata management, makes paleoecological data openly available, and offers a high-quality, curated resource. Neotoma’s distributed scientific governance model is flexible and scalable, with many open pathways for participation by new members, data contributors, stewards, and research communities. The Neotoma data model supports, or can be extended to support, any kind of paleoecological or paleoenvironmental data from sedimentary archives. Data additions to Neotoma are growing and now include >3.8 million observations, >17,000 datasets, and >9200 sites. Dataset types currently include fossil pollen, vertebrates, diatoms, ostracodes, macroinvertebrates, plant macrofossils, insects, testate amoebae, geochronological data, and the recently added organic biomarkers, stable isotopes, and specimen-level data. Multiple avenues exist to obtain Neotoma data, including the Explorer map-based interface, an application programming interface, the neotoma R package, and digital object identifiers. As the volume and variety of scientific data grow, community-curated data resources such as Neotoma have become foundational infrastructure for big data science.

2,4-D has been reported to antagonize glyphosate activity on grass weed species. In addition, sodium bicarbonate antagonized 2,4-D activity on broadleaf species. Experiments were conducted using Nuclear Magnetic Resonance (NMR) technology to evaluate interactions of 2,4-D dimethylamine and 2,4-D butoxyethylester formulations with glyphosate in solution. The 2,4-D dimethylamine formulation associated with glyphosate to form the dimethylamine salt of glyphosate. NMR spectra also showed that the molecular orientation of the glyphosate molecule was affected by the 2,4-D butoxyethylester formulation. The antagonist was not the active 2,4-D butoxyethylester molecule itself, but appeared to be due to an association of glyphosate with organic components in the 2,4-D butoxyethylester formulation. The molecular influence of sodium bicarbonate on technical grade 2,4-D free acid, and dimethylamine and butoxyethylester formulations was also evaluated. Sodium bicarbonate was found to react with the 2,4-D free acid and 2,4-D dimethylamine to form the sodium salt of 2,4-D. The 2,4-D butoxyethylester formulation did not react with sodium bicarbonate.

In the discipline of Weed Science, nuclear magnetic resonance (NMR) has been used extensively for obtaining structural information on herbicide compounds in the areas of herbicide synthesis, metabolism, and environmental degradation. However, little research has been published with regard to the utilization of NMR in determining molecular interactions in the spray solution. The molecular influence of citric add and an organosilicone adjuvant on glyphosate was analyzed with NMR spectrometry. 14C-glyphosate absorption studies showed a decrease in glyphosate absorption by sunflower when Ca2+ was added to the spray solution. This absorption antagonism was overcome with the inclusion of an organosilicone adjuvant. 1H-NMR was used to stow that the organosilicone adjuvant did not directly interact with the glyphosate molecule nor did it prevent the formation of Ca-glyphosate. Citric add was effective in overcoming the Cat2+ antagonism of glyphosate activity when the citric add concentration was 2× or 4× the Ca2+ molar concentration based on plant fresh weight and plant height, respectively. 1H-NMR was utilized to show that citric acid reacted with Ca2+ in solution to produce Ca-citrate and prevent the formation of Ca-glyphosate. NMR was an effective technique for characterizing chemical interactions among the spray solution components.

The antagonistic effect of Na-bentazon on sethoxydim absorption and herbicidal activity has been documented. The addition of ammonium sulfate (AMS) with a surfactant overcomes the observed loss of sethoxydim activity. Nuclear Magnetic Resonance (NMR) was used to study the chemical effects of commercially formulated Na-bentazon, NaCl, NaHCO3, Na-bentazon plus AMS, and NaHCO3 plus AMS on commercially formulated sethoxydim. Technical grade Li-sethoxydim and sethoxydim were analyzed and 1H-NMR spectra were used as comparative standards. Data indicate an association of Na+ from Na-bentazon, NaHCO3, and NaCl with the sethoxydim molecule. NH4+ from AMS appears to associate spatially with sethoxydim but does not exert the same electronic effect on the sethoxydim ring protons as observed with Na+ or Li+. The addition of AMS to sethoxydim plus Na-bentazon or NaHCO3 treatments prevents the complexation of Na+ with the sethoxydim molecule. The data support the hypothesis that the observed Na-bentazon antagonism and ammonium sulfate reversal of antagonism are chemically based.

Hard-water cations, such as Ca+2 and Mg+2, present in the spray solution can greatly reduce the efficacy of glyphosate. These cations potentially compete with the isopropylamine in the formulation for association with the glyphosate anion. 14C-Glyphosate absorption by sunflower was reduced in the presence of Ca+2. The addition of ammonium sulfate overcame the observed decrease in 14C-glyphosate absorption. Nuclear Magnetic Resonance (NMR) was used to study the chemical effects of calcium and calcium plus ammonium sulfate (AMS) on the glyphosate molecule. Data indicate an association of calcium with both the carboxyl and phosphonate groups on the glyphosate molecule. Initially, a random association of the compounds occurred; however, the reaction progressed to yield a more structured, chelate type complex over time. NH4+ from AMS effectively competed with calcium for complexation sites on the glyphosate molecule. Data suggest that the observed calcium antagonism of glyphosate and AMS reversal of the antagonism are chemically based.

The variability of radiocarbon marine reservoir age through time and space limits the accuracy of chronologies in marine paleo-environmental archives. We report here new radiocarbon reservoir ages (ΔR) from the central coast of Chile (~ 32°S) for the Holocene period and compare these values to existing reservoir age reconstructions from southern Peru and northern Chile. Late Holocene ΔR values show little variability from central Chile to Peru. Prior to 6000 cal yr BP, however, ΔR values were markedly increased in southern Peru and northern Chile, while similar or slightly lower-than-modern ΔR values were observed in central Chile. This extended dataset suggests that the early Holocene was characterized by a substantial increase in the latitudinal gradient of marine reservoir age between central and northern Chile. This change in the marine reservoir ages indicates that the early Holocene air–sea flux of CO2 could have been up to five times more intense than in the late Holocene in the Peruvian upwelling, while slightly reduced in central Chile. Our results show that oceanic circulation changes in the Humboldt system during the Holocene have substantially modified the air–sea carbon flux in this region.

The Christensen Mastodon Site, located in central Indiana, contains a rich assemblage of vertebrates (including mastodon, caribou, and giant beaver), invertebrates, and plant macrofossils in situ in lake and bog sediments of late-glacial age. Studies of pollen and plant macrofossils suggest the existence of open, white spruce-dominated boreal forests from > 14,000 yr B.P. to ca. 13,000 yr B.P. The regional decline of spruce, local occurrence of black spruce, white spruce, and larch, immigration of many hardwood taxa (e.g., ash, oak, elm), and the initiation of bog development are recorded beginning about 13,000 yr B.P. Recent reconstructions of late-glacial and early postglacial vegetational changes provide a context for understanding the disappearance of mastodons. The dramatic and rapid restriction of boreal forests along the retreating ice margin from 11,000 to 9000 yr B.P. may have caused a substantial reduction of mastodon populations. A diminished population would be more susceptible to small-scale, stochastic events such as short-term extremes of weather, outbreaks of disease, or predation pressure from paleoindian hunters.

Pollen and plant macrofossil analyses and dating (both TAMS and conventional 14 C) of wetland sediments from the Nodoroc Site in the Piedmont region of northeastern Georgia identified two depositional episodes of interstadial (ca. 26,000-22,000 yr B.P.) and mid- to late Holocene (<3600 yr B.P.) age. Interstadial pollen assemblages were dominated by Pinus and Quercus, with Carya, Picea, and Abies also present in significant amounts. The interstadial assemblages had lower Pinus and higher Quercus pollen percentages than apparently contemporaneous assemblages from sites in the southern Appalachians and Coastal Plain. Interstadial macrofossils included two needle morphotypes of Pinus subgenus Pinus, possibly indicating local occurrence of two Pinus species. One of the needle morphotypes is consistent with Pinus banksiana, but other species cannot be ruled out. Comparison of conventional and TAMS 14C dates illustrates problems in obtaining accurate age models from wetlands and ponds characterized by shallow or fluctuating water levels, low sedimentation rates, and vegetation growing on the depositional surface.

The United States dependence on fossil fuels has become mandatory over the past few decades. The fuel shortage during the 1970s and after Hurricane Katrina has catalyzed a need for creating alternative energy sources, improving the efficacy of these alternative energy sources, and enhancing energy sustainability. The U.S. Department of Energy has set goals to replace 30% of the liquid petroleum transportation fuel with biofuels and to replace 25% of industrial organic chemicals with biomass-derived chemicals by 2025. In the southeast United States, subterranean termites are prevalent and microbes in their gut degrade wood based materials such as cellulose which produce simple sugars that can be used to produce bioethanol. Upon seasonal change, subterranean termites undergo less enzymatic activity and wood-eating capability limiting the amount of sugars that may be produced. This limited activity sparks an interest to investigate this poorly understood phenomenon of how temperature may affect the enzymatic activity in subterranean termites’ guts. In this study, we report the development thermoresponsive biomaterial nanofiber mats containing cellulose to model cellulase activity. Using electrospinning techniques, poly(N-vinylcaprolactam) celluose fiber mats have been prepared via alkaline hydrolysis and labeled with fluorescent tags. Subterranean termites (reticulitermes species) were feed fiber mats for 10 consecutive days to assess enzyme mapping and kinetics. Fluorescent microscopy images confirmed spatial and temporal localization of cellulase enzyme throughout the termite gut upon time and temperature change. These novel high affinity enzyme detection membranes show promise towards future biofuel production.

Water availability in the semiarid western coast of Chile (30–32°S) is conditioned by high interannual precipitation variability, reflecting the transition between arid subtropical and moist mid-latitude climates in the Southeastern Pacific Ocean. A paleoclimate reconstruction based on the latest Pleistocene–Holocene geological record from the Quebrada Santa Julia archeological site in Chile (31°50′S) and on modern meteorological mechanisms producing alluvial episodes in this region indicates a major change in the rainfall regime shortly after 8600 cal yr BP. This, together with other paleoclimate proxies along the west coast of South America (34°–14°S), suggests La Niña-like conditions 13,000–8600 cal yr BP. Based on sedimentological and geomorphologic evidence, we hypothesized that the absence of heavy rainfall events in northern Chile and the new hydrological regime that prevailed ca. 8600–5700 cal yr BP in north-central Chile resulted from an increase in the large-scale westerly flow over central Chile, as expected in near-neutral ENSO conditions. This atmospheric circulation anomaly is compatible with an equatorward shift of the influence of the Southeast Pacific Subtropical Anticyclone relative to the early Holocene, prior to the onset of modern ENSO variability.

In this work, a very efficient mixed-potential integral-equation formulation is implemented for the rigorous analysis of multilayered structures with arbitrarily shaped two-dimensional periodic metallic and/or dielectric inclusions. Original acceleration techniques have been developed for the computation of the components of the scalar and dyadic Green's functions, based on different types of asymptotic extractions according to the potential considered. The theoretical approach and its computational convenience have been validated through different full-wave analyses concerning both scattering problems and complex-mode dispersive behaviors in various frequency-selective structures for microwave applications.

According to current thinking, the peopling of South America involved a coastal as well as an inland exploitation. Here the authors describe a camp that may denote a transition between the two. As indicated by bifacial tools, the investigation shows that people began to move inland and hunt mammals around 8500 cal BP, perhaps in association with a change in the climate.

Researchers in the High Andes in northern Chile report the study of a fine cave sequence, supported by 19 radiocarbon dates. The initial occupation at c. 11 500 cal BP represents the earliest human occupation known at this altitude. The toolkit suggests a hunting (logistical) camp used to take advantage of the animals gathering in the rich wetland of the neighbourhood.

This article identifies ways to overcome impediments to restoring natural features on developed shores where human-use functions are the dominant driving forces. Suggestions are made for (1) incorporating natural features and natural dynamism into beach nourishment projects; (2) addressing constraints in size and space; (3) reducing the impact of human actions and elements in the landscape; (4) integrating endangered species programmes; (5) overcoming impediments to implementing restoration projects; (6) conducting post-construction evaluations and actions; (7) obtaining public support; and (8) addressing regulatory issues. Beach nourishment projects can better mimic natural landforms, while protecting infrastructure and habitat, creating space for dunes, and providing sediment for dune building. Dunes can have more value as habitat if sub-environments representative of natural gradients are accommodated. Greater human effort will be required to maintain both dynamic and stable zones for habitat, and these zones may be restricted to smaller scales. Controls can be placed on human actions, such as raking the beach, driving on the beach, walking through the dune, emplacing more structures than necessary and introducing exotic vegetation for landscaping. Regulatory restrictions that now prevent environmentally friendly actions can be eased, and adaptive management and education programmes can be implemented.