Exercises on the Nature of Science: The Necessity of Observation

The key to understanding and explaining the physical world around us is observation. The recent study Vegetation Communities of Ledges State Park, Boone County, Iowa Johnson-Groh, 1985) is largely observation. On the other extreme, even the most theoretical research done with paper, pencil and computer must be compared with observations of that which it hopes to explain. The first step in doing science, or studying science, is to observe

Exercises on the Nature of Science: Indirect Observations

An earlier ISTJ article (Stout, 1986) presented several methods for demonstrating the importance of observation in scientific inquiry. The blue bottle demonstration described there illustrates the use of indirect observations in science. The demonstration described here carries the concept of indirect observation further. It can stand alone, or be integrated with the blue bottle demonstration for a more complete discussion of the nature of science

Teaching Good Writing, Why Bother?

In this article, the author discusses why there is a need for science teachers to teach writing to the students when the English teachers can do it better. He asserts that teaching the students to write well provides them a powerful thinking and learning tool. Another reason is to train the students to become more efficient spokespersons for science. The opinion of Antonine Lavoisier, who states, "It is impossible to dissociate language from science or science from language.... To call forth a concept a word is needed" is also cited

Pressure Oscillations in Adiabatic Compression

The article discusses an experiment on the behavior of pressure oscillations in adiabatic compression. The author states, "After finding Moloney and McGarvey's modified adiabatic compression apparatus, I decided to insert this experiment into my physical chemistry laboratory at the last minute, replacing a problematic experiment. With insufficient time to build the apparatus, we placed a bottle between two thick textbooks and compressed it with a third textbook forced down from above. We discovered that approximately one in three trials exhibited a damped pressure oscillation after compression, making it difficult to determine the true peak pressure. We discarded these trials and used only those without oscillation. I subsequently have had time to build a version of Moloney and McGarvin's apparatus. Using this apparatus, my students and I have recently performed numerous adiabatic compression trials with three different gases, with very few instances of oscillation.

"The Chemicals Project": Connecting General Chemistry to Students' Lives

"The Chemicals Project" described here strives to bring freshman chemistry alive for students by emphasizing its connection to the real world and to their own lives and experiences. Its major assignments deal with chemical phobias, recognizing the chemicals found in everyday life and chemical hazards (using Material Data Safety Sheets). The project is described in a cooperative learning format, employs portfolio grading, and includes a significant writing component. Ways of linking this project with the course lecture and student evaluations of the project are described. The bottom line: pre- and post-testing shows that it works. The Chemicals Project brings chemistry alive for students

"Hello, I'm Carbon.": Writing about Elements and Compounds

General chemistry students are asked to assume the identity of an element and to write their own story. In the spirit of pedagogical approaches such as writing-to-learn and writing across the curriculum, this assignment has several objectives, most significantly to connect students to the discipline of chemistry in a robust way. Facilitating this process writing assignment and evaluating it using a three-dimensional grading rubric are discussed. Suggestions of how to convince students to write a story rather than a report and summaries of four student autobiographies are given. The article discusses the assignment grading and other mechanics used in the experiment. It shows the traits of good and poor elemental autobiographies used in assessing the assignment. The feedback of the experiment is also presented

C02 Investigations: An Open Inquiry Experiment for General Chemistry.

This paper presents a successful, free inquiry experiment in which students devise an experiment to measure carbon dioxide in an important chemical, biological, or environmental situation. Also discussed is a rationale for adopting an open inquiry experiment and how it fits into the laboratory as a whole. Typical student projects are given, and data showing this experiment's success are presented and discussed

Stromelysin-3 over-expression enhances tumourigenesis in MCF-7 and MDA-MB-231 breast cancer cell lines: involvement of the IGF-1 signalling pathway

BACKGROUND: Stromelysin-3 (ST-3) is over-expressed in the majority of human carcinomas including breast carcinoma. Due to its known effect in promoting tumour formation, but its impeding effect on metastasis, a dual role of ST-3 in tumour progression, depending on the cellular grade of dedifferentiation, was hypothesized. METHODS: The present study was designed to investigate the influence of ST-3 in vivo and in vitro on the oestrogen-dependent, non-invasive MCF-7 breast carcinoma cell line as well as on the oestrogen-independent, invasive MDA-MB-231 breast carcinoma cell line. Therefore an orthotopic human xenograft tumour model in nude mice, as well as a 3D matrigel cell culture system, were employed. RESULTS: Using both in vitro and in vivo techniques, we have demonstrated that over-expression of ST-3 in MCF-7 and MDA-MB-231 cells leads to both increased cell numbers and tumour volumes. This observation was dependent upon the presence of growth factors. In particular, the enhanced proliferative capacity was in MCF-7/ST-3 completely and in MDA-MB-231/ST-3 cells partially dependent on the IGF-1 signalling pathway. Microarray analysis of ST-3 over-expressing cells revealed that in addition to cell proliferation, further biological processes seemed to be affected, such as cell motility and stress response. The MAPK-pathway as well as the Wnt and PI3-kinase pathways, appear to also play a potential role. Furthermore, we have demonstrated that breast cancer cell lines of different differentiation status, as well as the non-tumourigenic cell line MCF-10A, have a comparable capability to induce endogenous ST-3 expression in fibroblasts. CONCLUSION: These data reveal that ST-3 is capable of enhancing tumourigenesis in highly differentiated "early stage" breast cancer cell lines as well as in further progressed breast cancer cell lines that have already undergone epithelial-mesenchymal transition. We propose that ST-3 induction in tumour fibroblasts leads to the stimulation of the IGF-1R pathway in carcinoma cells, thus enhancing their proliferative capacity. In addition, further different cellular processes seem to be activated by ST-3, possibly accounting for the dual role of ST-3 in tumour progression and metastasis

Sarcomeric Pattern Formation by Actin Cluster Coalescence

Contractile function of striated muscle cells depends crucially on the almost crystalline order of actin and myosin filaments in myofibrils, but the physical mechanisms that lead to myofibril assembly remains ill-defined. Passive diffusive sorting of actin filaments into sarcomeric order is kinetically impossible, suggesting a pivotal role of active processes in sarcomeric pattern formation. Using a one-dimensional computational model of an initially unstriated actin bundle, we show that actin filament treadmilling in the presence of processive plus-end crosslinking provides a simple and robust mechanism for the polarity sorting of actin filaments as well as for the correct localization of myosin filaments. We propose that the coalescence of crosslinked actin clusters could be key for sarcomeric pattern formation. In our simulations, sarcomere spacing is set by filament length prompting tight length control already at early stages of pattern formation. The proposed mechanism could be generic and apply both to premyofibrils and nascent myofibrils in developing muscle cells as well as possibly to striated stress-fibers in non-muscle cells

The Changing Face of Neolithic and Bronze Age Ireland: A Big Data Approach to the Settlement and Burial Records

This paper synthesizes and analyses the spatial and temporal patterns of archaeological sites in Ireland spanning the Neolithic period and the Bronze Age transition (4300-1900 cal BC). Included are a large number of unpublished, newly discovered sites excavated through development-led projects. Data were also sourced from national archives, published excavation reports and on-line databases. Software tools were developed to deal with the varying nature and resolution of these datasets, allowing chronology to be considered in the analysis to a degree that is usually not possible in prehistoric studies. Summed radiocarbon probabilities are used to examine the dataset using context- and sample-sensitive approaches. Visualisations of spatial and chronological data illustrate the expansion of Early Neolithic settlement, followed by an apparent attenuation of all settlement activity. The Late Neolithic and Chalcolithic periods are characterised by a resurgence and diversification of activity. To assess the significance of these observations, Irish radiocarbon data are compared to an idealized model derived from North American data. Even after taking various considerations into account, human population increases can be suggested to have occurred during the Early and Late Neolithic periods. Gaps and biases in the data are discussed and priorities for future work are identified