19,492 research outputs found
Eigenhearts for diagnosis of congestive heart failure (CHF)
Common cardiac diseases such as cardio-myopathy, coronary artery diseases, and valve diseases, result in abnormal myocardial movement, which could eventually lead to heart failure, also called congestive heart failure (CHF). CHF is a disease in which the heart's ability to pump blood efficiently is lost. Possible presence of this disease and location of the abnormal activity can be diagnosed from patient's scan images, by determining the wall motion abnormalities. In this paper, a new principal component analysis (PCA) technique, Eigenhearts, is presented to diagnose the abnormal contractility of heart wall. Experiments were carried out using a preliminary set of simulated scan data and the results are discussed
Spot sampling of nutrient concentrations in the Puarenga catchment, Rotorua
The Centre for Biodiversity and Ecology Research was approached by Tūhourangi Tribal Authority for assistance with measuring water quality in streams in the Puarenga Stream catchment. Water sampling was subsequently undertaken on 18 July 2011 and samples were analysed to determine concentrations of total and dissolved fractions of nitrogen and phosphorus.
Nitrogen and phosphorus are both essential plant nutrients which, when present in excess, can cause eutrophication and associated water quality decline of freshwaters. High concentrations of dissolved forms of nitrogen can also be toxic to aquatic organisms. Excessive nitrogen and phosphorus concentrations are typically the result of pollution due to human activities, although groundwater in the Central Volcanic Plateau region can have elevated concentrations of phosphorus arising from natural geological sources.
This report summarises the methods used, presents the results and places measured concentrations in context by drawing comparisons with both guideline and regional mean values
Welfare-to-Work Program Benefits and Costs: A Synthesis of Research
Most welfare programs seek to ensure that poor families have adequate income while at the same time encouraging self-sufficiency. Based on studies of 28 programs involving more than 100,000 sample members, this synthesis compares the costs, benefits, and returns on investment of six welfare program strategies -- from the perspectives of participants, government budgets, and society as a whole
Improving detection probabilities for pests in stored grain
BACKGROUND: The presence of insects in stored grains is a significant problem for grain farmers, bulk grain handlers and distributors worldwide. Inspections of bulk grain commodities is essential to detect pests and therefore to reduce the risk of their presence in exported goods. It has been well documented that insect pests cluster in response to factors such as microclimatic conditions within bulk grain. Statistical sampling methodologies for grains, however, have typically considered pests and pathogens to be homogeneously distributed throughout grain commodities. In this paper we demonstrate a sampling methodology that accounts for the heterogeneous distribution of insects in bulk grains. RESULTS: We show that failure to account for the heterogeneous distribution of pests may lead to overestimates of the capacity for a sampling program to detect insects in bulk grains. Our results indicate the importance of the proportion of grain that is infested in addition to the density of pests within the infested grain. We also demonstrate that the probability of detecting pests in bulk grains increases as the number of sub-samples increases, even when the total volume or mass of grain sampled remains constant. CONCLUSION: This study demonstrates the importance of considering an appropriate biological model when developing sampling methodologies for insect pests. Accounting for a heterogeneous distribution of pests leads to a considerable improvement in the detection of pests over traditional sampling models
Expert system verification and validation study. ES V/V guidelines/workshop conference summary
The intent of the workshop was to start moving research on the verification and validation (V&V) of knowledge based systems (KBSs) in the direction of providing tangible 'products' that a KBS developer could use. In the near term research will focus on identifying the kinds of experiences encountered during KBS development of 'real' KBSs. These will be stored in a repository and will serve as the foundation for the rest of the activities described here. One specific approach to be pursued is 'benchmarking'. With this approach, a KBS developer can use either 'canned' KBSs with seeded errors or existing KBSs with known errors to evaluate a given tool's ability to satisfactorily identify errors
Modelling the response of a highly eutrophic lake to reductions in external and internal nutrient loading
The reduction of macronutrients to levels that limit primary production is often a critical element of mitigating eutrophication and reducing the potential for algal blooms. Lake Okaro has remained highly eutrophic despite an intensive catchment and in-lake restoration programme, including implementation of a constructed wetland, riparian protection, an alum application and application of a modified zeolite mineral (Z2G1) to reduce internal nutrient loading. A one-dimensional process-based ecosystem model (DYRESM-CAEDYM) was used in this study to investigate the need for further nutrient loading reductions of both nitrogen (N) and phosphorus (P). The model was calibrated against field data for a 2-year period and validated over two separate 1-year periods. Model simulations suggest that the trophic status of the lake, measured quantitatively with the Trophic Level Index (TLI), could shift from highly eutrophic to mesotrophic with external and internal loads of both N and P reduced by 75-90%. The magnitude of the nutrient load reductions is indicative of a major challenge in being able to effect transitions across trophic state categories for eutrophic lakes
High Temperature Superfluidity in Double Bilayer Graphene
Exciton bound states in solids between electrons and holes are predicted to
form a superfluid at high temperatures. We show that by employing atomically
thin crystals such as a pair of adjacent bilayer graphene sheets, equilibrium
superfluidity of electron-hole pairs should be achievable for the first time.
The transition temperatures are well above liquid helium temperatures. Because
the sample parameters needed for the device have already been attained in
similar graphene devices, our work suggests a new route towards realizing
high-temperature superfluidity in existing quality graphene samples.Comment: 6 pages, 4 figures, effect of screening on superfluidity include
IRRIGATION EFFICIENCY, WATER STORAGE, AND LONG RUN WATER CONSERVATION
A spreadsheet-based simulation model is used to illustrate the complex relationships between irrigation efficiency, water banking and water conservation under the prior appropriation doctrine. Increases in irrigation efficiency and/or establishment of water banks do not guarantee water conservation. Conservation requires reduction in the quantity of water consumptively used by agriculture.Land Economics/Use,
Knowledge-based system V and V in the Space Station Freedom program
Knowledge Based Systems (KBS's) are expected to be heavily used in the Space Station Freedom Program (SSFP). Although SSFP Verification and Validation (V&V) requirements are based on the latest state-of-the-practice in software engineering technology, they may be insufficient for Knowledge Based Systems (KBS's); it is widely stated that there are differences in both approach and execution between KBS V&V and conventional software V&V. In order to better understand this issue, we have surveyed and/or interviewed developers from sixty expert system projects in order to understand the differences and difficulties in KBS V&V. We have used this survey results to analyze the SSFP V&V requirements for conventional software in order to determine which specific requirements are inappropriate for KBS V&V and why they are inappropriate. Further work will result in a set of recommendations that can be used either as guidelines for applying conventional software V&V requirements to KBS's or as modifications to extend the existing SSFP conventional software V&V requirements to include KBS requirements. The results of this work are significant to many projects, in addition to SSFP, which will involve KBS's
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