67,760 research outputs found
Preparing Preservice Teachers for the Experimental Design and Data Analysis SOL\u27s
Many elementary teachers ļ¬nd teaching the science Standards of Learning (SOL) difficult [1, 2]. Some are even threatened by them. Of particular concern are the SOLs related to experimental design, handling data, and the scientific method. A possible reason for this discomfort is because many of these elementary teachers have had limited-to-no exposure to experimentation. As one of the activities included under a recent National Science Foundation Science Teachers Enhancement Project (STEP) grant awarded to Hampton University in conjunction with Virginia Union University and St. Paul\u27s College, we included a teacher science fair competition. A special workbook/text was developed for this project and used to guide teachers through the research process; from observation, and hypothesis formation and testing through the evaluation of data and drawing conclusions from the experiment. Twenty-two teachers from the Richmond metropolitan area and King and Queen County developed individual projects (laboratory research), and prepared written reports and display boards to present their results. Projects were adjudicated by staff at the Science Museum of Virginia in a formal competition for teachers. Several teachers admitted that this was the ļ¬rst time that they had actually performed a full experiment. All participants agreed, at. the end, that they had a much better understanding of the process, and would be better able to teach it to their students. This successful activity is being submitted to the review panel as a reproducible model which affords preservice teachers an opportunity to strengthen their research skills. It can also make teachers feel more conļ¬dent, and equip them to do a better job of teaching this block of SOLs
An optimal internet location strategy for markets with different tax rates
The traditional view that a high sales tax rate reduces trade by driving a wedge between the purchase and sale price may not apply to internet commerce for two reasons. The first reason is that the sales tax paid by buyers purchasing via the internet is determined by the tax rate in the region of the buyer. The second reason is that a high sales tax may lower the before-tax price if sellers absorb part of the tax. Taken together, this implies that internet distributors may profitably target customers in regions with low tax rates by locating their selling addresses in high tax regions. Consequently the optimal marketing strategy for a global internet distributor may include siting selling locations in regions with high tax rates in order to target customers in regions with low tax rates. An empirical analysis of the European car market suggests that this is more than a remote theoretical possibility by demonstrating that the before-tax prices recommended by manufacturers for new cars are lower in high tax countries
Searching a biomedical bibliographic database from the Ukraine: the Panteleimon database
The Panteleimon database is available via the Internet and is a public access, database, capable of being searched in English, Russian and Ukrainian, covering medical, pharmaceutical, and chemical publications, published in he Ukraine and Russia from 1998. Describes the formulation of a search strategy for the Panteleimon database, for the identification of citations to randomized controlled trials (RCTs), and the comparison of the search results with records included in the Cochrane Library's Cochrane Central Register of Controlled Trials (CENTRAL) database, to evaluate how comprehensive the coverage of the CENTRAL database is for the literature of the Ukraine. The results indicated that Panteleimon is an easily accessible bibliographic database offering easy access to the Ukrainian biomedical literature. The English language retrieval functions picked up most of the reports of RCTs/CCTs (91 per cent precision but the lower recall of 55 per cent indicates the need to search using Russian and Ukrainian terms for completeness. The overall precision of 26 per cent compares favourably with a search for RCTs in EMBASE, carried out by the UK Cochrane Centre, where 70,000 reports of RCTs were identified from 300,000 records down-loaded (precision 23 per cent). (Quotes from original text
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Assessing the Effect of Photodynamic Therapy on Peripheral Nerve and Cancer Cells Using a Thin Tissue Engineered Collagen Culture Model
Abstract not available
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Intracellular localisation of mTHPC and effect of photodynamic therapy in cells of the mammalian peripheral nervous system
Fewer nerve-related side effects have been noted after treating head and neck cancer with photodynamic therapy (PDT) compared to conventional cancer therapy. Our aim is to investigate the biological basis for any such nerve-sparing effect. In this study the intracellular localisation and effect on cell viability of the photosensitiser meta-tetrahydroxylphenylchlorin (mTHPC) was investigated in cell culture models using peripheral nerve cells.
Primary cells from adult rat dorsal root ganglia (containing both neurons and glia) were used in these experiments. Localisation of mTHPC was detected using fluorescence and confocal microscopy. Levels of mTHPC fluorescence were quantified using digital image analysis. Immunocytochemistry with anti-?-III-tubulin and anti-S100 was used to distinguish neuronal and glial cell populations respectively. A cell-death assay using propidium iodide was used to evaluate neural cell susceptibility to PDT following incubation with mTHPC.
The results showed that mTHPC was localised in cytoplasmic regions of neurons and glia, but was not detected in neuronal axons. Necrotic cell death was detected after PDT in these neural cell types.
These results suggest that the cells of the peripheral nervous system are susceptible to PDT-mediated necrosis, but that the sparing of nerves observed during clinical PDT may be related to the heterogeneous distribution of mTHPC within neurons
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Differences in sensitivity to mTHPC-mediated photodynamic therapy of neurons, glial cells and MCF7 cells in a 3-dimensional cell culture model
The effect of photodynamic therapy (PDT) on the cells of the nervous system is an important consideration in the treatment of tumours that are located within or adjacent to the brain, spinal cord and peripheral nerves. Previous studies have reported the sparing of nerves during PDT using meta-tetrahydroxyphenylchlorin (mTHPC, FoscanĀ®) in patients and in animal models. The aim of this study was to investigate the effects of mTHPC on key nervous system cells using a 3-dimensional cell culture system for the accurate detection of differences in sensitivity
Development of thermal control methods for specialized components and scientific instruments at very low temperatures (follow-on)
Many payloads currently proposed to be flown by the space shuttle system require long-duration cooling in the 3 to 200 K temperature range. Common requirements also exist for certain DOD payloads. Parametric design and optimization studies are reported for multistage and diode heat pipe radiator systems designed to operate in this temperature range. Also optimized are ground test systems for two long-life passive thermal control concepts operating under specified space environmental conditions. The ground test systems evaluated are ultimately intended to evolve into flight test qualification prototypes for early shuttle flights
A measurable effect of general relativity in satellite orbits
Relativistic corrections calculated for one way Doppler system used in calculating orbital velocit
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