2,265 research outputs found
An algorithm to compare two‐dimensional footwear outsole images using maximum cliques and speeded‐up robust feature
Footwear examiners are tasked with comparing an outsole impression (Q) left at a crime scene with an impression (K) from a database or from the suspect\u27s shoe. We propose a method for comparing two shoe outsole impressions that relies on robust features (speeded‐up robust feature; SURF) on each impression and aligns them using a maximum clique (MC). After alignment, an algorithm we denote MC‐COMP is used to extract additional features that are then combined into a univariate similarity score using a random forest (RF). We use a database of shoe outsole impressions that includes images from two models of athletic shoes that were purchased new and then worn by study participants for about 6 months. The shoes share class characteristics such as outsole pattern and size, and thus the comparison is challenging. We find that the RF implemented on SURF outperforms other methods recently proposed in the literature in terms of classification precision. In more realistic scenarios where crime scene impressions may be degraded and smudged, the algorithm we propose—denoted MC‐COMP‐SURF—shows the best classification performance by detecting unique features better than other methods. The algorithm can be implemented with the R‐package shoeprintr
Turbulent Pumping of Magnetic Flux Reduces Solar Cycle Memory and thus Impacts Predictability of the Sun's Activity
Prediction of the Sun's magnetic activity is important because of its effect
on space environment and climate. However, recent efforts to predict the
amplitude of the solar cycle have resulted in diverging forecasts with no
consensus. Yeates et al. (2008) have shown that the dynamical memory of the
solar dynamo mechanism governs predictability and this memory is different for
advection- and diffusion-dominated solar convection zones. By utilizing
stochastically forced, kinematic dynamo simulations, we demonstrate that the
inclusion of downward turbulent pumping of magnetic flux reduces the memory of
both advection- and diffusion-dominated solar dynamos to only one cycle;
stronger pumping degrades this memory further. Thus, our results reconcile the
diverging dynamo-model-based forecasts for the amplitude of solar cycle 24. We
conclude that reliable predictions for the maximum of solar activity can be
made only at the preceding minimum--allowing about 5 years of advance planning
for space weather. For more accurate predictions, sequential data assimilation
would be necessary in forecasting models to account for the Sun's short memory.Comment: 4 figures, 1 tabl
An approach to propagate streamflow statistics along the river network
Streamflow at ungauged sites is often predicted by means of regional statistical procedures. The standard regional approaches do not preserve the information related to the hierarchy among gauged stations deriving from their location along the river network. However, this information is important when estimating runoff at a site located immediately upstream or downstream of a gauging station. We propose here a novel approach, referred to as the Along-Stream Estimation (ASE) method, to improve runoff estimation at ungauged sites. The ASE approach starts from the regional estimate at an ungauged (target) site, and corrects it based on regional and sample estimates of the same variable at a donor site, where sample data are available. A criterion to define the domain of application around each donor site of the ASE approach is proposed, and the uncertainty inherent in the estimates obtained is evaluated. This allows one to compare the variance of the along-stream estimates to that of other models that eventually become available for application (e.g. regional models), and thus to choose the most accurate method (or to combine different estimates). The ASE model was applied in the northwest of Italy in connection with an existing regional model for flood frequency analysis. The analysed variables are the first L-moments of the annual discharge maxima. The application demonstrates that the ASE approach can be used effectively to improve the regional estimates for the L-moment of order one (the index flood), particularly when the area ratio of a pair of donor-target basins is less than or equal to ten. However, in this case study, the method does not provide significant improvements to the estimation of higher-order L-moment
Measure for measure: pack performance versus human dexterity and grip strength
‘Openability’ of food and beverage packaging has been shown to be problematic for older consumers.
Pressure on resources has seen the use of packaged food and beverages increase in hospitals within the
New South Wales region of Australia. Studies at the University of Wollongong have explored the interaction
between older people and the types of packages regularly encountered in the delivery of hospital food
and nutrition. As these types of packs are commonly found in UK hospitals as well, a series of studies have
been undertaken by the University of Wollongong, Australia, and Sheffield Hallam University, UK, to
further evaluate the issues surrounding the ‘openability’ of hospital food and beverage packaging in an
attempt to understand in detail the issues leading to difficulty in use.
Current methods of pack ‘ease of opening’ evaluation rely on hand strength as the core parameter. Our
studies examine the role of dexterity in addition to hand strength in pack opening. Water bottles, single portion
drink cartons and cheese portions were among the poorest performing packs. Dexterity, rather than
strength is found to be a sensitive and reliable method to understand the issues surrounding the poor pack
performance, and a repeatable way of comparing different pack formats is presented
Finite-sample-size effects on convection in mushy layers
We report theoretical and experimental investigations of the flow instability
responsible for the mushy-layer mode of convection and the formation of
chimneys, drainage channels devoid of solid, during steady-state solidification
of aqueous ammonium chloride. Under certain growth conditions a state of steady
mushy-layer growth with no flow is unstable to the onset of convection,
resulting in the formation of chimneys. We present regime diagrams to quantify
the state of the flow as a function of the initial liquid concentration, the
porous-medium Rayleigh number, and the sample width. For a given liquid
concentration, increasing both the porous-medium Rayleigh number and the sample
width caused the system to change from a stable state of no flow to a different
state with the formation of chimneys. Decreasing the concentration ratio
destabilized the system and promoted the formation of chimneys. As the initial
liquid concentration increased, onset of convection and formation of chimneys
occurred at larger values of the porous-medium Rayleigh number, but the
critical cell widths for chimney formation are far less sensitive to the liquid
concentration. At the highest liquid concentration, the mushy-layer mode of
convection did not occur in the experiment. The formation of multiple chimneys
and the morphological transitions between these states are discussed. The
experimental results are interpreted in terms of a previous theoretical
analysis of finite amplitude convection with chimneys, with a single value of
the mushy-layer permeability consistent with the liquid concentrations
considered in this study
Occupational safety and regulatory compliance in US commercial fishing
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Taylor & Francis for personal use, not for redistribution. The definitive version was published in Archives of Environmental & Occupational Health 66 (2011): 209-216, doi:10.1080/19338244.2011.564237.This study explored occupational safety practices and regulatory compliance in a
representative sample of Maine commercial fishing vessels. Data were collected on
demographic characteristics, safety equipment and training, and regulatory compliance
during at sea boardings of working commercial fishing vessels (n=259). Trends in safety
and compliance were explored using standard comparison tests and principal component
analysis. More than 40% of vessels were not in compliance with applicable safety
regulations. That rate was lower for fishermen subjected to more stringent and costly
safety requirements. The vast majority of fishermen were not safety trained, and many
were not familiar with the proper use and maintenance of life-saving equipment. There is
a clear need for better safety training in this industry. Educational efforts should be
targeted at the local level at minimal cost to fishermen to encourage participation.This study was supported by funding from Maine Sea Grant and the National Oceanic and Atmospheric Administration (R/08-03 NA060AR4170108)
Distribution of coronal and root caries experience among persons aged 60+ in South Australia
The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included.This report provides epidemiological data describing caries experience among the population of non-institutionalized older adults in Adelaide and Mt Gambier. Subjects were selected in a stratified random sample of persons aged 60+ who were listed on the South Australian Electoral Database. Oral examinations were conducted by four calibrated dentists among 853 dentate persons aged 60 years and over. There was an average of 14.7 missing teeth, 8.3 filled teeth and 0.3 decayed teeth, and a further 0.2 teeth were present as retained roots. The mean number of missing teeth was higher (p < 0.05) in older compared with younger age groups, and in Mt Gambier compared with Adelaide. The mean DFS of 22.1 was significantly higher (p < 0.05) among younger persons, females and in Adelaide. Root surface caries affected an average of 3.1 surfaces, and was greater (p < 0.05) among persons aged 70-79 years, males and Adelaide residents. However, when root caries was expressed as an attack rate per 100 exposed surfaces, differences were statistically significant only among age groups. Analysis of specific teeth revealed that no more than 40 per cent of molars were retained, and between 30 and 58 per cent of retained molars had coronal fillings.Gary D. Slade, A. John Spence
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