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We offer a course that our majors enroll in concurrently with their calculus course that “shadows” the topics covered by the calculus professor. In the shadow course, the students work collaboratively to build mathematical skills and apply calculus concepts to solve geoscience problems provided by the instructor (two examples are given). Students earn a grade of “pass” by demonstrating their involvement in learning. It is not feasible to assess statistically the effect of the shadow course on students' grades in the calculus courses; however, the shadow course has led to other positive outcomes. Our majors have developed more positive attitudes toward mathematics, including calculus, and get the message that geoscience faculty value and actively support their learning of calculus. We have gained insight into our students' strengths and weaknesses in mathematics that may help us to incorporate mathematics more effectively into geoscience courses. The shadow course is helping to foster active collaboration among geoscience and mathematics faculty that strengthens the teaching of scientific problem-solving using quantitative methods in both the calculus and the shadow courses.

Assembly jobs often require sustained, awkward neck and/or shoulder postures. It has been shown in previous studies that these postures increase musculoskeletal discomfort and can impact long-term productivity. The aim of this study was to investigate the effects of ergonomic interventions designed to eliminate these awkward postures. Subjects used a cordless screwdriver to drive screws into a pre-tapped aluminum block, simulating a simple assembly task. Four distinct assembly postures were tested: standard industry (in-line screwdriver, work at elbow height, no visual aid), pistol grip (pistol grip screwdriver, work at shoulder height, no visual aid), mirror (in-line screwdriver, work at elbow height, single mirror visual aid) and periscope (in-line screwdriver, work at elbow height, two mirror visual aids). Each was performed for fifteen minutes. Muscular activity, discomfort, postural deviation from neutral, productivity, and operator subjective assessment were recorded to determine the effects of the interventions. Both interventions (mirror and periscope) resulted in lower muscle activity, smaller postural deviations from neutral and lower subjective discomfort levels. Productivity, however, was highest in the standard industry posture followed by the pistol grip (9% lower), the periscope (13% lower) and the mirror posture (23% lower).

Statistical analysis of one version of the magnetic reversal record suggests that the frequency of reversals has changed cyclically with a period of 30 Myr starting at least 165 Myr ago. But factors other than periodicity affect the analysis used and here I show that there is no compelling evidence for periodicity in the reversal record. The results of essentially identical analyses that have been applied to other geolocial data should also be re-evaluated.

We present a quantitative model for in situ crystallization within a solidification zone (or boundary layer) based on the trace and major element compositions of plutonic igneous rocks and related geochemical data. We developed the model to account for the characteristics of a suite of granitic rocks: nearly uniform mineral compositions in rocks that range widely in bulk composition (e.g., 58–76 wt.% SiO2); linear variation and correlation of all major and trace elements analyzed except Ba; large and apparently random variations in Ba concentration. These characteristics cannot be explained by any standard petrogenetic model involving fractionation, mixing, or restite unmixing, but are successfully reproduced by our model of residual melt migration. We do not attempt to model the entire crystallization history of a pluton but, rather, only that interval during which melt migration processes have recognizable geochemical effects. For the granitic suite, the chemical signature of residual melt migration resulted from the change in Ba compatibility with the onset of orthoclase crystallization at a granite minimum. Our results demonstrate that plutonic rocks can develop large compositional variations, comparable to those expected to result from extreme differentiation within a large magma body, over short distances by melt migration under conditions of high permeability or slow crystallization rate within the solidification zone. Melt migration is probably a common process that could be overlooked in large plutons if sampling is sparse and if variations in some components that appear random are not considered.

The spatial distribution of magmatic activity may provide important information about magma formation, magma transport through the lithosphere, and the mechanical properties of the lithosphere. Zones of weakness in the crust, tentatively associated with deep crustal fractures, have been hypothesized to control the locations of magmatic centers. A connection between some lineaments and large-scale crustal structures suggests that magma emplacement could be controlled by sets of fractures with linear outcrop patterns. In this case, the locations of magmatic centers would not be distributed randomly but would have an anisotropic component. Thus, identification and characterization of such anisotropic control is a valuable exercise.

We report here the results of a series of inclusive chemical characterizations, including all elements except oxygen, for a suite of 54 tourmaline samples. A combination of analytical techniques was used to analyze for major and light elements (electron microprobe), Fe3+ and Fe2+ (Mossbauer spectroscopy), H (U extraction), and B, Li, and F (ion microprobe, or SIMS). The B content of the tourmalines studied ranges from 2.86 to 3.26 B per formula unit (pfu) with 31 anions; excess boron is believed to reside in the Si site. Li ranges from 0.0 to 1.44 Li pfu and F contents are 0.0-0.91 pfu. H contents range from nearly anhydrous up to 3.76 H pfu and do not correlate simply with Fe3+ content.

In case of an emergency in an underground coal mine, miners who fail to escape from the mine can enter a refuge alternative (RA) for protection from adverse conditions, such as high carbon monoxide levels. One of the main concerns with the use of both portable and built-in-place (BIP) RAs, especially for hot or deep mines, is the interior temperature rise due to the occupants' metabolic heat and the heat released by devices such as the carbon dioxide (CO2) scrubbing system. The humidity within the RA will also increase through occupants' respiration and perspiration and from the chemical reaction within the CO2 scrubbing system. Heat and humidity buildup can subject the occupants to hazardous thermal conditions. To protect RA occupants, Mine Safety and Health Administration regulations mandate a maximum apparent temperature of 95 °F within an occupied RA. The National Institute for Occupational Safety and Health (NIOSH) tested both an air-conditioned borehole air supply (BAS) and a cryogenic air supply for RAs in the NIOSH Experimental Mine in Bruceton, PA. The BAS was tested on a 60-person BIP RA, while the cryogenic air supply was tested on a 30-person BIP RA and a portable 23-person tent-type RA. Multiple tests were conducted with both air supplies to assess their ability to cool RAs. The test results show that the BAS and the cryogenic air supply were able to maintain the apparent temperature within the tested RAs under the 95 °F limit. The BAS and the cryogenic air supply are potential RA heat mitigation strategies that mines could use to prevent heat/humidity buildup within RAs.

Several studies have suggested a period of about 30 Myr in the frequency of geomagnetic reversal1–4superposed on a long-term variation, but none of these studies explicitly investigated the effects of the long-term variation on their analyses. We show that the long-term variations alone account for most of the spectral evidence taken to support the 30 Myr periodicity. In particular, high peaks in the spectra near 30 Myr, the overall pattern of peaks, and shifts of the peak pattern for subsets of the data are explained well by a long-term variation model. We suggest that there may be periodic changes in reversal frequency about the long-term variation, but that more study will be required before the periodicity can be established.