Evaluation of Nebraska’s Aggregate Reactivity by the Miniature Concrete Prism Test Method – AASHTO T380

The evaluation of nine different aggregates shows the viability of the T380 test method as an alternative to the standard C1293 test method. The T380 assesses the Alkali-Silica Reaction potential of aggregates with the same reliability as C1293 and correlates well with the C1293 test method. Results are obtained within 56 days by T380 compared to 365 days required by C1293. The T380 method at 56 days appears to characterize the aggregate reactivity similarly to C1293 for all the aggregates evaluated in this study. Therefore, T380 will be part of the Department test method for approval of interground/blended cements along with the ASTM C1567-Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate. The Department has changed the specification for approving IP or IT cements to allow the use of T380 after the Department has completed the test method C1567. Per the specification, the mortar bars shall not exceed 0.10% expansion at 28 days while performing C1567. If the expansion is greater than 0.10% at 28 days while performing C1567, then the interground/blended cements shall be tested in accordance with AASHTO T380 using fine aggregate from an approved Platte River Valley and/or Elkhorn River aggregate source with an expansion not greater than 0.02% at 56 days

Compressive Strength of Concrete Cylinders by Different Preparation Methods: Sulphur, Neoprene Pads and Grinding

The purpose of this evaluation is to compare the effects of four types of cylinder preparation methods prior to compressive strength testing in accordance to ASTM C 39

Effect of Moisture Condition on Concrete Core Strengths

The main purpose of this study was to determine if there would be any major differences between curing methods of cores taken for acceptance testing from a highway slab on a project. The comparison provided data to determine the effect of the moisture gradients created by these different curing treatments on core strength and core permeability. The strengths were measured of moist cured cores and sealed plastic bag cured cores from the day cores were obtained (14, 21 and 26 days) until they reached 28 days. Permeability was also measured at 26, 28 and 32 days. According to ASTM C42, it is current practice to allow the cores to remain in a sealed condition with a plastic bag or non-absorbent containers for at least 5 days prior to testing unless otherwise specified by the engineer. Currently, Nebraska Department of Transportation (NDOT) follows the ASTM C42 with the exception that all cores obtained for compressive strength testing must be delivered to the PCC Lab in a sealed bag, un-bagged and stored immediately in a moist cure room until the required 28-day testing. The findings from this study show no significant difference in strength nor in permeability between curing concrete core samples in bags versus storing them in a moist room

We Mean Green Environmental Science Club

Lesson Plans for an Environmental Science Club. This club seeks to promote environmental awareness to elementary students through hands-on activities, videos, and discussion

Pain Control in the African Context: the Ugandan introduction of affordable morphine to relieve suffering at the end of life

Dr Anne Merriman is the founder of Hospice Africa and Hospice Africa Uganda. She is presently Director of Policy and International Programmes. Here she tells the story of how HAU was founded. Dr Richard Harding is an academic researcher working on palliative care in Sub-Saharan Africa. This paper described Dr Merriman's experience in pioneering palliative care provision. In particular it examines the steps to achieving wider availability of opioids for pain management for those with far advanced disease. Hospice Africa Uganda has been a model facility in achieving high quality clinical care embedded in a strategy of advocacy and education, using a multifaceted approach that has addressed logistical, policy and legislative barriers. Until 1990 control of severe pain in Sub-Saharan Africa was non-existent except in Zimbabwe and S Africa. Oral affordable morphine was brought to Kenya through Nairobi Hospice that year, and to Uganda through Hospice Africa Uganda in 1993. This paper offers an example of a highly effective and cost efficient model of care that has transformed the ability to humanely manage the problems of those with terminal illness, and to offer a culturally appropriate "good death". Thus it is now possible to complete the ethical circle of care in resource poor circumstances

Ambiguity aversion under maximum-likelihood updating

Maximum likelihood updating (MLU) is a well-known approach for extending static ambiguity sensitive preferences to dynamic set-ups. This paper develops an example in which MLU induces an ambiguity averse maxmin expected utility (MEU) decision-maker to (i) prefer a bet on an ambiguous over a risky urn and (ii) be more willing to bet on the ambiguous urn compared to an (ambiguity neutral) subjective expected utility (SEU) decision-maker. This is challenging since prior to observing (symmetric) draws from the urns, the MEU decision-maker (in line with the usual notion of ambiguity aversion) actually preferred the risky over the ambiguous bet and was less willing to bet on the ambiguous urn than the SEU decision-maker. The identified switch in betting preferences is not due to a violation of dynamic consistency or consequentialism. Rather, it results from MLU's selection of extreme priors, causing a violation of the stability of set-inclusion over the course of the updating process