Groundwater and Surface Water Contributions to Metals Loading in Bayhorse Creek at the Abandoned Ramshorn Mine Site Near Bayhorse, Idaho

Many abandoned mines in the United States are littered with waste metals that leach into watersheds and degrade habitats. Although metals-laden waters may appear pristine, fish bioaccumulate high concentrations of metals in their tissues, which create health risks if consumed by humans. This study examines the source and fate of metals in Bayhorse Creek near the abandoned Ramshorn mine outside of Challis, Idaho. In 2003, the U.S. Geological Survey found high levels of arsenic, cadmium, chromium, copper, lead, silver, and zinc in soils adjacent to the tailings pile. The Idaho Department of Environmental Quality authorized remediation to begin in summer 2011 without fully comprehending the source and fate of contaminants into the creek. Metals loads were determined along the reach of Bayhorse Creek adjacent to the mine by measuring the flow rates of streams and groundwater seeps, and collecting water samples for chemical analysis. The chemical controls on metals mobility and attenuation in the surface and groundwater at the site were determined by computer modeling, a diffuse double-layer surface complexation model and the geochemical program PHREEQC. Dissolved and suspended arsenic, copper, iron, manganese, lead, and zinc load the creek. The lowest site along the creek consistently measured as the highest load. Arsenic, copper, and lead loads were relatively insignificant compared to iron and manganese. The results indicate that 47% or more of the iron and manganese travel as metal-oxides, and arsenic and zinc tend to sorb to ferrous oxides. Large metals fluxes between SW-1 and SW-5 and at SW-8 suggest tailings and waste rock located between SW-1 and SW-5 and the slag pile adjacent to SW-8 are the main sources of metals contamination. Concentrations below the EPA drinking water standards and the absence of acidic pH indicate that the main metals loading consists of safe levels of iron, manganese, and zinc

Inside the Mentors’ Experience: Using Poetic Representation to Examine the Tensions of Mentoring Pre-Service Teachers.

The supervision and mentoring of pre-service teachers during professional experience is complex work that requires a range of skills and capacities. Professional development for this work has traditionally been limited, however, and mentor teachers report experiencing tensions in their work stemming from their roles as both supporter and assessor of pre-service teachers. Despite the central role that mentors play in professional experience, their voices are underrepresented in the literature. In this paper, I draw on interview data to examine teachers’ experiences as mentors and the tensions they experience. I use poetic representation to illuminate the tensions and emotions of mentoring and present seven poems that provide insight into these tensions. I argue that poetic representation of interview data provides an opportunity to connect with the experience of being a mentor and offer suggestions for teacher educators to work collaboratively with mentor teachers to explore the dimensions of their role

Combined analysis of KamLAND and Borexino neutrino signals from Th and U decays in the Earth's interior

The KamLAND and Borexino experiments have detected electron antineutrinos produced in the decay chains of natural thorium and uranium (Th and U geoneutrinos). We analyze the energy spectra of current geoneutrino data in combination with solar and long-baseline reactor neutrino data, with marginalized three-neutrino oscillation parameters. We consider the case with unconstrained Th and U event rates in KamLAND and Borexino, as well as cases with fewer degrees of freedom, as obtained by successively assuming for both experiments a common Th/U ratio, a common scaling of Th+U event rates, and a chondritic Th/U value. In combination, KamLAND and Borexino can reject the null hypothesis (no geoneutrino signal) at 5 sigma. Interesting bounds or indications emerge on the Th+U geoneutrino rates and on the Th/U ratio, in broad agreement with typical Earth model expectations. Conversely, the results disfavor the hypothesis of a georeactor in the Earth's core, if its power exceeds a few TW. The interplay of KamLAND and Borexino geoneutrino data is highlighted.Comment: 12 pages, including 6 figure

Geo-neutrinos

We review a new interdisciplinary field between Geology and Physics: the study of the Earth's geo-neutrino flux. We describe competing models for the composition of the Earth, present geological insights into the make up of the continental and oceanic crust, those parts of the Earth that concentrate Th and U, the heat producing elements, and provide details of the regional settings in the continents and oceans where operating and planned detectors are sited. Details are presented for the only two operating detectors that are capable of measuring the Earth's geo-neutrinos flux: Borexino and KamLAND; results achieved to date are presented, along with their impacts on geophysical and geochemical models of the Earth. Finally, future planned experiments are highlighted

A comparative study investigating the enablers and barriers facing teacher educators in a regional university: Snapshots from 2013 and 2020.

Although the provision of initial teacher education has been the subject of more than 100 inquiries and multiple reforms, the work of those in teacher education remains under-researched. This comparative research provides two snapshots of teacher educator surveys conducted seven years apart (2013 and 2020) in a regional university in Australia. The primary aim of the research was to examine how teacher educators describe their work and goals and to identify the barriers and enablers that are present in their practice. The data were thematically coded and categorised. The outcomes highlight that personal and professional experiences do shape the goals and motivations of teacher educators; that knowledge and skills impact the ways that they enact their work, and that professional development is essential. Issues pertaining to the discipline of teacher education and an increasingly casualised workforce need to be addressed by those within and external to the profession

Expectations of efficient actions bias social perception : a pre-registered online replication

Funding This work was supported by the Leverhulme Trust (grant no. RPG-2019-248) awarded to P.B.Peer reviewedPublisher PD

Missing Data, Imputation, and Endogeneity

Basmann (Basmann, R.L., 1957, A generalized classical method of linear estimation of coefficients in a structural equation. Econometrica 25, 77-83; Basmann, R.L., 1959, The computation of generalized classical estimates of coefficients in a structural equation. Econometrica 27, 72-81) introduced two-stage least squares (2SLS). In subsequent work, Basmann (Basmann, R.L., F.L. Brown, W.S. Dawes and G.K. Schoepfle, 1971, Exact finite sample density functions of GCL estimators of structural coefficients in a leading exactly identifiable case. Journal of the American Statistical Association 66, 122-126) investigated its finite sample performance. Here, we build on this tradition focusing on the issue of 2SLS estimation of a structural model when data on the endogenous covariate is missing for some observations. Many such imputation techniques have been proposed in the literature. However, there is little guidance available for choosing among existing techniques, particularly when the covariate being imputed is endogenous. Moreover, because the finite sample bias of 2SLS is not monotonically decreasing in the degree of measurement accuracy, the most accurate imputation method is not necessarily the method that minimizes the bias of 2SLS. Instead, we explore imputation methods designed to increase the first-stage strength of the instrument(s), even if such methods entail lower imputation accuracy. We do so via simulations as well as with an application related to the medium-run effects of birth weight

Dynamic Panel Data Models with Irregular Spacing: With Applications to Early Childhood Development

With the increased availability of longitudinal data, dynamic panel data models have become commonplace. Moreover, the properties of various estimators of such models are well known. However, we show that these estimators breakdown when the data are irregularly spaced along the time dimension. Unfortunately, this is an increasingly frequent occurrence as many longitudinal surveys are collected at non-uniform intervals and no solution is currently available when time-varying covariates are included in the model. In this paper, we propose several new estimators for dynamic panel data models when data are irregularly spaced and compare their finite sample performance to the nai¨ve application of existing estimators. We illustrate the practical importance of this issue by turning to two applications on early childhood development