The teaching of linear programming in different disciplines and in different countries

This paper discusses an online survey of linear programming (LP) lecturers in four countries in various disciplines. The study uses Biglan’s [1, 2] classification of disciplines to show that courses in hard-pure and hard-applied subjects were more likely to teach theoretical aspects of linear programming whilst the hard-applied and soft-applied subjects looked more at the application. Further, the soft-applied disciplines were more likely to utilize software during the teaching of the topic. Also, US lecturers were more likely to teach theoretical aspects of LP whilst the UK lecturers were more likely to use common software such as spreadsheets rather than dedicated LP or maths software

Measuring Producer Level Beef Cattle Alliance Financial Performance

There has been a movement toward developing production and marketing alliances in the beef cattle sector in the United States to improve communications and ultimately provide higher priced branded products consistent with consumer demand. Beef cattle producers do not employ a consistent methodology to measure the financial performance of alliance participation. Nor do they have the information to negotiate financially sustainable agreements. The concentrated packer and retail sector do not share cost and returns information beyond total business data required by public traded corporations. A methodology using cost accounting and economic analysis is described to measure return on producer's assets for an alliance agreement. This information can be used to inform the margin sectors, feedyards, packers and retailers on what share of increased revenue from branded product sales to pass to the cow-calf segment to make participation competitive and the alliance financially sustainable. The cow-calf segment must absorb the added costs and cyclical financial loss to participate in alliances. Increased revenue is required to make branded products a more profitable marketing option than producing commodity beef.Agricultural Finance, Livestock Production/Industries,

An Extinction Threshold for Protostellar Cores in Ophiuchus

We have observed continuum emission at lambda = 850 microns over ~4 square degrees of the Ophiuchus star-forming cloud using SCUBA on the JCMT, producing a submillimetre continuum map twenty times larger than previous Ophiuchus surveys. Our sensitivity is 40 mJ/beam, a factor of ~2 less sensitive than earlier maps. Using an automated identification algorithm, we detect 100 candidate objects. Only two new objects are detected outside the boundary of previous maps, despite the much wider area surveyed. We compare the submillimetre continuum map with a map of visual extinction across the Ophiuchus cloud derived using a combination of 2MASS and R-band data. The total mass in submillimetre objects is ~ 50 Msun compared with ~ 2000 Msun in observed cloud mass estimated from the extinction. The submillimetre objects represent only 2.5% of the cloud mass. A clear association is seen between the locations of detected submillimetre objects and high visual extinction, with no objects detected at A_V<7 magnitudes. Using the extinction map, we estimate pressures within the cloud from P/k ~2x10^5 cm^-3 K in the less-extincted regions to P/k ~2x10^6 cm^-3 K at the cloud centre. Given our sensitivities, cold (T_d ~15K) clumps supported by thermal pressure, had they existed, should have been detected throughout the majority of the map. Such objects may not be present at low A_V because they may form only where A_V > 15, by some mechanism (e.g., loss of non-thermal support).Comment: 12 pages, 1 figure. Accepted by Astrophysical Journal Letter

PORT ELEVATOR CAPACITY AND NATIONAL AND WORLD GRAIN SHIPMENTS

An analysis is conducted on the port component of the United States grain export system. A transshipment model is utilized which covers both United States internal and foreign shipments of corn, soybeans, and wheat during the four quarters of a year. The model suggests that there will be quarter to quarter constraints on port capacity but that annual capacity is adequate. Through sensitivity analysis a number of key factors were found which influence the adequacy of the current port system. Port adequacy is found to depend not as much on export market location as it does on domestic transportation rates and policies.International Relations/Trade,

Mathematical thinking of undergraduate students when using three types of software

The research investigates how conceptual understanding of mathematics is promoted when using three types of software: black-box (no mathematical intermediate steps shown), glass-box (intermediate steps shown) and open-box (interaction at each intermediate step). Thirty-eight students were asked to think-aloud and give detailed explanations whilst answering three types of tasks: mechanical (mostly procedural), interpretive (mostly conceptual) and constructive (mixture of conceptual and procedural). The software types had no impact on how students answered the mechanical tasks; however students using the black-box did better on the constructive tasks because of their increased explorations. Students with low maths confidence resorted to using real-life explanations when answering tasks that were application related

An Illustration of Students’ Engagement with Mathematical Software using Remote Observation

Students using three types of spreadsheet calculators for understanding expected value were observed remotely. This remote observation involves the use of webcams and application sharing for observing students learning mathematics. The study illustrates how remote observation can be used for collecting mathematical education data and raises questions about the extent to which such a method can be used in future experiments

Technology - Empowering the Educational Researcher through Remote Observation

Observing students using computers often occurs through three methods: user-lab, on-site and remote data logging. Whilst each of these have their advantages with the new type of students such as elearners, an alternative method called web-conferencing remote observation is presented for observing students at a distance. This method collects both audio and video data of the observer through webcams and voice/video conversations. Students are able to interact with the software through application sharing facilities. Further, it allows both quantitative and qualitative data to be collected. This proof-of-concept method is presented here where it has been used in two previous studies using Windows Messenger and Netviewer. Although, video quality is not high the quality is sufficient for observational data