THE IMPACT OF RECLAMATION ON ACCEPTABLE STRIP MINING ROYALTY PAYMENTS

Resource /Energy Economics and Policy,

Computer Self-Efficacy, Digital Learners, and Completion Rates in the California Community College System

The importance of online learning in higher education has increased considerably over the last two decades. As a result, online learning has become an important area of research. The purpose of the study was to examine if higher levels of computer self-efficacy (CSE) contributed to online course completion among online California community college students. Guided by Bandura’s (1977) work on self-efficacy and the work of Compeau and Higgins (1995) and Howard (2014) on computer self-efficacy, this study revealed that there is no relationship between high levels of CSE and successful completion of the course. A judgement sample was used to select five online sections from a northern California community college in which 122 students participated. These students completed a Computer User Self-efficacy questionnaire which consisted of 12 questions on a six-point Likert scale as well as three questions regarding their perceived use of computers. Spearman’s Correlation Coefficient was conducted to see if a relationship existed between high levels of computer self-efficacy and course grades. The results showed that there was no statistically significant relationship between high levels of computer self-efficacy and course grades. The implication of this study suggests that computer self-efficacy may not be an important factor for today’s digital learner

Computer Self-Efficacy, Digital Learners, and Completion Rates in the California Community College System

The importance of online learning in higher education has increased considerably over the last two decades. As a result, online learning has become an important area of research. The purpose of the study was to examine if higher levels of computer self-efficacy (CSE) contributed to online course completion among online California community college students. Guided by Bandura’s (1977) work on self-efficacy and the work of Compeau and Higgins (1995) and Howard (2014) on computer self-efficacy, this study revealed that there is no relationship between high levels of CSE and successful completion of the course. A judgement sample was used to select five online sections from a northern California community college in which 122 students participated. These students completed a Computer User Self-efficacy questionnaire which consisted of 12 questions on a six-point Likert scale as well as three questions regarding their perceived use of computers. Spearman’s Correlation Coefficient was conducted to see if a relationship existed between high levels of computer self-efficacy and course grades. The results showed that there was no statistically significant relationship between high levels of computer self-efficacy and course grades. The implication of this study suggests that computer self-efficacy may not be an important factor for today’s digital learner

The Warm Ionized Medium in the Milky Way and Other Galaxies

Observations of the "Warm Ionized Medium" (or, equivalently, the "Diffuse Ionized Gas") of the local ISM, the Perseus arm in the Milky Way, and also in several other galaxies show strong [NII]6563 (~H-alpha in some cases) and [SII]6717/[NII]6583 = 0.6 - 0.7 in all locations and objects. Other line ratios (e.g., [O III]5007/H-beta) vary considerably. Simple photoionization models reproduce the observed spectra, providing extra heating beyond that supplied by photoionization is assumed (Reynolds, Haffner, & Tufte 1999). With observed gas-phase abundances (not solar), the line ratios in the local arm at b = 0 deg are fitted with no extra heating and (S/H) = 13 ppm (solar is 20 ppm). Local gas observed at b = -35 deg requires extra heating of about gamma = 0.75, where gamma is the extra heating in units of 10^{-25} erg H^{-1} s^{-1}. In the Perseus arm, there are similar results, with a domposition consistent with the Galactic abundance gradient. The requirements for NGC 891 are similar to the Perseus arm: little or no extra heating at |z| = 1 kpc and gamma 3 at 2 kpc. In NGC 891 there is also an increase of 5007/H-alpha with |z| that can only come about if most of the ionizing radiation is supplied by stars with T~50000 K. Either their radiation must propagate from the plane to high |z| through very little intervening matter, or else the stars are located at high |z|. The total power requirement of the extra heating is <15% of the photoionization power. [O~II]3727/H-beta can serve as a useful diagnostic of extra heating, but [S~III] 9065,9531/H-alpha is not useful in this regard.Comment: 32 pages, including 2 figures. To appear in November 20 Ap

Monte Carlo Photoionization Simulations of Diffuse Ionized Gas

We demonstrate that the observed increase of some nebular line ratios with height above the midplane in the diffuse ionized gas (DIG) in the Milky Way and other galaxies is a natural consequence of the progressive hardening of the radiation field far from the midplane ionizing sources. To obtain increasing temperatures and line ratios away from the midplane, our photoionization simulations of a multi-component interstellar medium do not require as much additional heating (over and above that from photoionization) as previous studies that employed one dimensional, spherically averaged models. Radiation leaking into the DIG from density bounded H II regions is generally harder in the H-ionizing continuum and has its He-ionizing photons suppressed compared to the ionizing source of the H II region. In line with other recent investigations, we find that such leaky H II region models can provide elevated temperatures and line ratios, and a lower He+ fraction in the DIG. For a composite model representing the relative spectral types of O stars in the solar neighbourhood, we find that additional heating less than 1.0E-26 n_e ergs/s/cm^3 can reproduce the observed elevated line ratios in the DIG. This additional heating is considerably less than previous estimates due to the natural hardening of the radiation field reaching large heights in our simulations.Comment: Accepted for publication in MNRA

Footprint of publication selection bias on meta-analyses in medicine, environmental sciences, psychology, and economics

Publication selection bias undermines the systematic accumulation of evidence. To assess the extent of this problem, we survey over 68,000 meta-analyses containing over 700,000 effect size estimates from medicine (67,386/597,699), environmental sciences (199/12,707), psychology (605/23,563), and economics (327/91,421). Our results indicate that meta-analyses in economics are the most severely contaminated by publication selection bias, closely followed by meta-analyses in environmental sciences and psychology, whereas meta-analyses in medicine are contaminated the least. After adjusting for publication selection bias, the median probability of the presence of an effect decreased from 99.9% to 29.7% in economics, from 98.9% to 55.7% in psychology, from 99.8% to 70.7% in environmental sciences, and from 38.0% to 29.7% in medicine. The median absolute effect sizes (in terms of standardized mean differences) decreased from d = 0.20 to d = 0.07 in economics, from d = 0.37 to d = 0.26 in psychology, from d = 0.62 to d = 0.43 in environmental sciences, and from d = 0.24 to d = 0.13 in medicine

Feeding and Distribution of Porosity in Cast Al-Si Alloys as Function of Alloy Composition and Modification

Unmodified, Na-modified, and Sr-modified castings of Al-7 pct Si and Al-12.5 pct Si alloys were cast in molds in which it was possible to create different cooling conditions. It is shown how solidification influences the distribution of porosity at the surface and the center of the castings as a function of modification and Si content in sand- and chill-cast samples. Eutectic modification, Si content, and cooling conditions have a great impact on the distribution of porosity. Unmodified and Na-modified castings are more easily fed with porosity tending to congregate near the centerline of the casting, while Sr-modified castings solidify in a mushy manner that creates a more homogeneous distribution of porosity in the casting. The amount of porosity was highest in the Sr-modified alloys, lower in the Na-modified alloys, and lowest in the unmodified alloys. The size of the porosity-free layer and the effectiveness of the feeders were greater in the castings made with the steel chills due to the increased thermal gradients and consequent increase in the directionality of solidification

Footprint of publication selection bias on meta-analyses in medicine, environmental sciences, psychology, and economics

Publication selection bias undermines the systematic accumulation of evidence. To assess the extent of this problem, we survey over 68,000 meta-analyses containing over 700,000 effect size estimates from medicine (67,386/597,699), environmental sciences (199/12,707), psychology (605/23,563), and economics (327/91,421). Our results indicate that meta-analyses in economics are the most severely contaminated by publication selection bias, closely followed by meta-analyses in environmental sciences and psychology, whereas meta-analyses in medicine are contaminated the least. After adjusting for publication selection bias, the median probability of the presence of an effect decreased from 99.9% to 29.7% in economics, from 98.9% to 55.7% in psychology, from 99.8% to 70.7% in environmental sciences, and from 38.0% to 29.7% in medicine. The median absolute effect sizes (in terms of standardized mean differences) decreased from d = 0.20 to d = 0.07 in economics, from d = 0.37 to d = 0.26 in psychology, from d = 0.62 to d = 0.43 in environmental sciences, and from d = 0.24 to d = 0.13 in medicine