Leaders’ distributional & efficiency effects in collective responses to policy: Lab-in-field experiments with small-scale gold miners in Colombia

2021 ◽  
Vol 147 ◽  
pp. 105648
Author(s):  
Luz A. Rodriguez ◽  
María Alejandra Velez ◽  
Alexander Pfaff
Keyword(s):  
Field Experiments ◽  
Small Scale ◽  
Gold Miners ◽  
Efficiency Effects

scholarly journals Applications of Chemically Modified Clay Minerals and Clays to Water Purification and Slow Release Formulations of Herbicides

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
Tomas Undabeytia ◽  
Uri Shuali ◽  
Shlomo Nir ◽  
Baruch Rubin
Keyword(s):  
Clay Minerals ◽  
Field Experiments ◽  
Slow Release ◽  
Freeze Fracture ◽  
Nano Particles ◽  
Organic Cations ◽  
Small Scale ◽  
High Exposure ◽  
Model Calculations ◽  
Slow Release Formulations

This review deals with modification of montmorillonite and other clay-minerals and clays by interacting them with organic cations, for producing slow release formulations of herbicides, and efficient removal of pollutants from water by filtration. Elaboration is on incorporating initially the organic cations in micelles and liposomes, then producing complexes denoted micelle- or liposome-clay nano-particles. The material characteristics (XRD, Freeze-fracture electron microscopy, adsorption) of the micelle– or liposome–clay complexes are different from those of a complex of the same composition (organo-clay), which is formed by interaction of monomers of the surfactant with the clay-mineral, or clay. The resulting complexes have a large surface area per weight; they include large hydrophobic parts and (in many cases) have excess of a positive charge. The organo-clays formed by preadsorbing organic cations with long alkyl chains were also addressed for adsorption and slow release of herbicides. Another examined approach includes “adsorptive” clays modified by small quaternary cations, in which the adsorbed organic cation may open the clay layers, and consequently yield a high exposure of the siloxane surface for adsorption of organic compounds. Small scale and field experiments demonstrated that slow release formulations of herbicides prepared by the new complexes enabled reduced contamination of ground water due to leaching, and exhibited enhanced herbicidal activity. Pollutants removed efficiently from water by the new complexes include (i) hydrophobic and anionic organic molecules, such as herbicides, dissolved organic matter; pharmaceuticals, such as antibiotics and non-steroidal drugs; (ii) inorganic anions, e.g., perchlorate and (iii) microorganisms, such as bacteria, including cyanobacteria (and their toxins). Model calculations of adsorption and kinetics of filtration, and estimation of capacities accompany the survey of results and their discussion.

How efficient are they really? A simple testing method of small-scale gold miners’ gravity separation systems

2017 ◽  
Vol 105 ◽  
pp. 44-51 ◽  
Author(s):  
Benjamin Teschner ◽  
Nicole M. Smith ◽  
Travis Borrillo-Hutter ◽  
Zira Quaghe John ◽  
Tony E. Wong
Keyword(s):  
Gravity Separation ◽  
Small Scale ◽  
Separation Systems ◽  
Testing Method ◽  
Gold Miners

scholarly journals Occupational and environmental mercury exposure among small-scale gold miners in the Talensi–Nabdam District of Ghana's Upper East region

2010 ◽  
Vol 408 (24) ◽  
pp. 6079-6085 ◽  
Author(s):  
Yasaswi Paruchuri ◽  
Amanda Siuniak ◽  
Nicole Johnson ◽  
Elena Levin ◽  
Katherine Mitchell ◽  
...  
Keyword(s):  
Mercury Exposure ◽  
Small Scale ◽  
East Region ◽  
Gold Miners ◽  
Upper East Region

Progress towards small-scale field trials of coastal enhanced weathering of olivine

2021 ◽  
Author(s):  
Stephen Romaniello ◽  
Shanee Stopnitzky ◽  
Tom Green ◽  
Francesc Montserrat ◽  
Eric Matzner ◽  
...  
Keyword(s):  
Real World ◽  
Field Experiments ◽  
Ecological Impact ◽  
Field Trials ◽  
Research Strategy ◽  
Unintended Consequences ◽  
Ecological Impacts ◽  
Small Scale ◽  
Climate Mitigation ◽  
Stage Of Development

<p>Slow progress towards achieving global greenhouse gas emissions targets significantly increases the likelihood that future climate efforts may require not only emissions cuts but also direct climate mitigation via negative emissions technologies (IPCC AR5). Currently, such technologies exist at only a nascent stage of development, with significant uncertainties regarding their feasibility, cost, and potential unintended consequences and/or co-benefits.</p><p>Coastal enhanced weathering of olivine (CEWO) has been suggested as one potential pathway for achieving net negative CO<sub>2</sub> emissions at scale. CEWO involves the mining of olivine-rich ultramafic rocks (such as dunite) for incorporation during beach augmentation and restoration work. While grinding this rock into increasingly fine particle sizes is essential for increasing its surface area and reactivity, this step is also costly and energetically expensive. CEWO attempts to minimize this cost and energy penalty by relying on wave and tidal action to provide ongoing physical weathering of olivine grains once distributed on beaches. Laboratory experiments and carbon emissions assessments of CEWO suggest that these approaches may be technically feasible and carbon negative, but significant uncertainties remain regarding the real-world kinetics of coastal olivine dissolution. Furthermore, concerns about the fate and ecological impact of nickel (Ni) and chromium (Cr)—potentially toxic trace metals found in olivine—require careful evaluation.</p><p>In 2019, Project Vesta was established as a nonprofit, philanthropically funded effort to evaluate the technical feasibility and ecological impacts of CEWO through a dedicated research program ultimately culminating in small-scale, real-world field trials of CEWO. This presentation will provide an overview and discussion of our overall research strategy, share insights from interim modeling and mesocosm experiments designed to ensure the practicality and safety of future field experiments, and explain our approach for ensuring transparent, responsible, and ethical research oversight and governance.</p>

Economic and social challenges faced by injured artisanal and small-scale gold miners in Kenya

2019 ◽  
Vol 118 ◽  
pp. 841-852 ◽  
Author(s):  
Michael Mayom Ajith ◽  
Apurna Kumar Ghosh
Keyword(s):  
Small Scale ◽  
Social Challenges ◽  
Gold Miners

Non-Linear Space-Time Evolution of Wave Groups With a High Crest

2003 ◽  
Author(s):  
Felice Arena ◽  
Francesco Fedele
Keyword(s):  
Time Evolution ◽  
Field Experiments ◽  
Surface Displacement ◽  
Fixed Time ◽  
Space Time ◽  
Second Order ◽  
Small Scale ◽  
Free Surface Displacement ◽  
Non Linear ◽  
Space Time Evolution

The theory of quasi-determinism, for the mechanics of linear three-dimensional waves, was obtained by Boccotti in the eighties. The first formulation of the theory deals with the largest crest amplitude; the second formulation deals with the largest wave height. The theory was verified in the nineties with some small-scale field experiments. In this paper the first formulation of Boccotti’s theory, valid for the space-time domain, is extended to the second order. The analytical expressions of the non-linear free surface displacement and velocity potential are obtained. Therefore the space-time evolution of a wave group, to the second-order in a Stokes expansion, when a very large crest occurs at a fixed time and location, is investigated. Finally the second-order probability of exceedance of the crest amplitude is obtained, as a function of two deterministic parameters.

scholarly journals Mission-driven research for stratospheric aerosol geoengineering

2019 ◽  
Vol 116 (4) ◽  
pp. 1089-1094 ◽  
Author(s):  
Douglas G. MacMartin ◽  
Ben Kravitz
Keyword(s):  
Radiative Forcing ◽  
Field Experiments ◽  
Research Effort ◽  
Science Research ◽  
Global Scale ◽  
Stratospheric Aerosol ◽  
Small Scale ◽  
Exploratory Research ◽  
Climate Risks ◽  
Research Activities

The last decade has seen broad exploratory research into stratospheric aerosol (SA) geoengineering, motivated by concern that reducing greenhouse gas emissions may be insufficient to avoid significant impacts from climate change. Based on this research, it is plausible that a limited deployment of SA geoengineering, provided it is used in addition to cutting emissions, could reduce many climate risks for most people. However, “plausible” is an insufficient basis on which to support future decisions. Developing the necessary knowledge requires a transition toward mission-driven research that has the explicit goal of supporting informed decisions. We highlight two important observations that follow from considering such a comprehensive, prioritized natural-science research effort. First, while field experiments may eventually be needed to reduce some of the uncertainties, we expect that the next phase of research will continue to be primarily model-based, with one outcome being to assess and prioritize which uncertainties need to be reduced (and, as a corollary, which field experiments can reduce those uncertainties). Second, we anticipate a clear separation in scale and character between small-scale experimental research to resolve specific process uncertainties and global-scale activities. We argue that the latter, even if the radiative forcing is negligible, should more appropriately be considered after a decision regarding whether and how to deploy SA geoengineering, rather than within the scope of “research” activities.

scholarly journals Attractiveness of thermally different, uniformly black targets to horseflies: Tabanus tergestinus prefers sunlit warm shiny dark targets

2019 ◽  
Vol 6 (10) ◽  
pp. 191119 ◽  
Author(s):  
Gábor Horváth ◽  
Ádám Pereszlényi ◽  
Tímea Tóth ◽  
Szabolcs Polgár ◽  
Imre M. Jánosi
Keyword(s):  
Field Experiments ◽  
Elevated Temperatures ◽  
Thermal Characteristics ◽  
Optical Characteristics ◽  
Degree Of Polarization ◽  
Small Scale ◽  
Host Animal ◽  
Reflected Light ◽  
Scale Models ◽  
Imaging Polarimetry

From a large distance tabanid flies may find their host animal by means of its shape, size, motion, odour, radiance and degree of polarization of host-reflected light. After alighting on the host, tabanids may use their mechano-, thermo-, hygro- and chemoreceptors to sense the substrate characteristics. Female tabanids prefer to attack sunlit against shady dark host animals, or dark against bright hosts for a blood meal, the exact reasons for which are unknown. Since sunlit darker surfaces are warmer than shady ones or sunlit/shady brighter surfaces, the differences in surface temperatures of dark and bright as well as sunlit and shady hosts may partly explain their different attractiveness to tabanids. We tested this observed warmth preference in field experiments, where we compared the attractiveness to tabanids ( Tabanus tergestinus ) of a warm and a cold shiny black barrel imitating dark hosts with the same optical characteristics. Using imaging polarimetry, thermography and Schlieren imaging, we measured the optical and thermal characteristics of both barrels and their small-scale models. We recorded the number of landings on these targets and measured the time periods spent on them. Our study revealed that T. tergestinus tabanid flies prefer sunlit warm shiny black targets against sunlit or shady cold ones with the same optical characteristics. These results support our new hypothesis that a blood-seeking female tabanid prefers elevated temperatures, partly because her wing muscles are more rapid and her nervous system functions better (due to faster conduction velocities and synaptic transmission of signals) in a warmer microclimate, and thus, she can avoid the parasite-repelling reactions of host animals by a prompt take-off.

Herbicide Inputs for a New Agronomic Crop, Annual Wormwood (Artemisia annua)

1991 ◽  
Vol 5 (1) ◽  
pp. 117-124 ◽  
Author(s):  
Charles T. Bryson ◽  
Edward M. Croom
Keyword(s):  
Clinical Trials ◽  
Weed Control ◽  
Crop Production ◽  
Large Scale ◽  
Field Experiments ◽  
Production Systems ◽  
Artemisia Annua ◽  
Small Scale ◽  
Herbicide Treatments ◽  
Large Scale Cultivation

Annual wormwood has been cultivated on a small scale for production of the artemisinin class of antimalarial drugs in sufficient quantities for preclinical and clinical trials. Large scale cultivation will require a reliable, efficient crop production system. Production systems using 32 herbicides alone or in combinations were evaluated in growth chamber, greenhouse, and field experiments at Stoneville, MS from 1985 through 1988. The herbicide treatments that provided the best weed control were (A) metolachlor at 2.2 kg ai ha-1preemergence (PRE), (B) chloramben at 2.2 kg ai ha-1(PRE), or (C) trifluralin at 0.6 kg ai ha-1preplant soil incorporated (PPI) followed by fluazifop at 0.2 + 0.2 kg ai ha-1postemergence broadcast (POST) and acifluorfen at 0.6 kg ai ha-1(POST). These herbicide production systems provided excellent weed control (≥85%) and minimal crop injury (≤10%) with no effect on crop height or weight at harvest. Production of artemisinin was not reduced by herbicide treatments A, B, and C in 1987 and treatments B and C in 1988 when compared with the hand-weeded plots.

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