333 research outputs found
The Jacobian as a measure of planar dose congruence
We propose a new starting point for comparing dose distributions in
therapeutic radiation physics using a Jacobian-based measure. The measure is
normalization independent, free of tunable parameters, bounded and converges to
a unique value when comparing unrelated dose distributions. We present a
preliminary demonstration of the sensitivity and general characteristics of
this measure.Comment: 9 pages, 2 figure
Dosimetric comparison of extended dose range film with ionization measurements in water and lung equivalent heterogeneous media exposed to megavoltage photons
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135483/1/acm20025.pd
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Clinic accessibility and clinic-level predictors of the geographic variation in 2009 pandemic influenza vaccine coverage in Montreal, Canada
Background: Nineteen mass vaccination clinics were established in Montreal, Canada, as part of the 2009 influenza A/H1N1p vaccination campaign. Although approximately 50% of the population was vaccinated, there was a considerable variation in clinic performance and community vaccine coverage. Objective: To identify community- and clinic-level predictors of vaccine uptake, while accounting for the accessibility of clinics from the community of residence. Methods: All records of influenza A/H1N1p vaccinations administered in Montreal were obtained from a vaccine registry. Multivariable regression models, specifically Bayesian gravity models, were used to assess the relationship between vaccination rates and clinic accessibility, clinic-level factors, and community-level factors. Results: Relative risks compare the vaccination rates at the variable's upper quartile to the lower quartile. All else being equal, clinics in areas with high violent crime rates, high residential density, and high levels of material deprivation tended to perform poorly (adjusted relative risk [ARR]: 0·917, 95% CI [credible interval]: 0·915, 0·918; ARR: 0·663, 95% CI: 0·660, 0·666, ARR: 0·649, 95% CI: 0·645, 0·654, respectively). Even after controlling for accessibility and clinic-level predictors, communities with a greater proportion of new immigrants and families living below the poverty level tended to have lower rates (ARR: 0·936, 95% CI: 0·913, 0·959; ARR: 0·918, 95% CI: 0·893, 0·946, respectively), while communities with a higher proportion speaking English or French tended to have higher rates (ARR: 1·034, 95% CI: 1·012, 1·059). Conclusion: In planning future mass vaccination campaigns, the gravity model could be used to compare expected vaccine uptake for different clinic location strategies
Investigation of Kodak extended dose range (EDR) film for megavoltage photon beam dosimetry
We have investigated the dependence of the measured optical density on the incident beam energy, field size and depth for a new type of film, Kodak extended dose range (Kodak EDR). Film measurements have been conducted over a range of field sizes (3 × 3 cm2 to 25 × 25 cm2) and depths (dmax to 15 cm), for 6 MV and 15 MV photons within a solid water phantom, and the variation in sensitometric response (net optical density versus dose) has been reported. Kodak EDR film is found to have a linear response with dose, from 0 to 350 cGy, which is much higher than that typically seen for Kodak XV film (0–50 cGy). The variation in sensitometric response for Kodak EDR film as a function of field size and depth is observed to be similar to that of Kodak XV film; the optical density varied in the order of 2–3% for field sizes of 3 × 3 cm2 and 10 × 10 cm2 at depths of dmax, 5 cm and 15 cm in the phantom. Measurements for a 25 × 25 cm2 field size showed consistently higher optical densities at depths of dmax, 5 cm and 15 cm, relative to a 10 × 10 cm2 field size at 5 cm depth, with 4–5% differences noted at a depth of 15 cm. Fractional depth dose and profiles conducted with Kodak EDR film showed good agreement (2%/2 mm) with ion chamber measurements for all field sizes except for the 25 × 25 cm2 at depths greater than 15 cm, where differences in the order of 3–5% were observed. In addition, Kodak EDR film measurements were found to be consistent with those of Kodak XV film for all fractional depth doses and profiles. The results of this study indicate that Kodak EDR film may be a useful tool for relative dosimetry at higher dose ranges.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48973/2/m22005.pd
Socio-Economic Disparities in the Burden of Seasonal Influenza: The Effect of Social and Material Deprivation on Rates of Influenza Infection
There is little empirical evidence in support of a relationship between rates of influenza infection and level of material deprivation (i.e., lack of access to goods and services) and social deprivation (i.e. lack of social cohesion and support).Using validated population-level indices of material and social deprivation and medical billing claims for outpatient clinic and emergency department visits for influenza from 1996 to 2006, we assessed the relationship between neighbourhood rates of influenza and neighbourhood levels of deprivation using Bayesian ecological regression models. Then, by pooling data from neighbourhoods in the top decile (i.e., most deprived) and the bottom decile, we compared rates in the most deprived populations to the least deprived populations using age- and sex-standardized rate ratios.Deprivation scores ranged from one to five with five representing the highest level of deprivation. We found a 21% reduction in rates for every 1 unit increase in social deprivation score (rate ratio [RR] 0.79, 95% Credible Interval [CrI] 0.66, 0.97). There was little evidence of a meaningful linear relationship with material deprivation (RR 1.06, 95% CrI 0.93, 1.24). However, relative to neighbourhoods with deprivation scores in the bottom decile, those in the top decile (i.e., most materially deprived) had substantially higher rates (RR 2.02, 95% Confidence Interval 1.99, 2.05).Though it is hypothesized that social and material deprivation increase risk of acute respiratory infection, we found decreasing healthcare utilization rates for influenza with increasing social deprivation. This finding may be explained by the fewer social contacts and, thus, fewer influenza exposure opportunities of the socially deprived. Though there was no evidence of a linear relationship with material deprivation, when comparing the least to the most materially deprived populations, we observed higher rates in the most materially deprived populations
Pluvio: Assembly Clone Search for Out-of-domain Architectures and Libraries through Transfer Learning and Conditional Variational Information Bottleneck
The practice of code reuse is crucial in software development for a faster
and more efficient development lifecycle. In reality, however, code reuse
practices lack proper control, resulting in issues such as vulnerability
propagation and intellectual property infringements. Assembly clone search, a
critical shift-right defence mechanism, has been effective in identifying
vulnerable code resulting from reuse in released executables. Recent studies on
assembly clone search demonstrate a trend towards using machine learning-based
methods to match assembly code variants produced by different toolchains.
However, these methods are limited to what they learn from a small number of
toolchain variants used in training, rendering them inapplicable to unseen
architectures and their corresponding compilation toolchain variants.
This paper presents the first study on the problem of assembly clone search
with unseen architectures and libraries. We propose incorporating human common
knowledge through large-scale pre-trained natural language models, in the form
of transfer learning, into current learning-based approaches for assembly clone
search. Transfer learning can aid in addressing the limitations of the existing
approaches, as it can bring in broader knowledge from human experts in assembly
code. We further address the sequence limit issue by proposing a reinforcement
learning agent to remove unnecessary and redundant tokens. Coupled with a new
Variational Information Bottleneck learning strategy, the proposed system
minimizes the reliance on potential indicators of architectures and
optimization settings, for a better generalization of unseen architectures. We
simulate the unseen architecture clone search scenarios and the experimental
results show the effectiveness of the proposed approach against the
state-of-the-art solutions.Comment: 13 pages and 4 figures. This work has been submitted to the IEEE for
possible publication. Copyright may be transferred without notice, after
which this version may no longer be accessibl
Enhanced spectral discrimination through the exploitation of interface effects in photon dose data
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134954/1/mp7731.pd
Contrasting biological potency of particulate matter collected at sites impacted by distinct industrial sources
Association of biological effects in A549 cells with metal content in size-fractionated particles. Cytotoxic potencies according to lactate dehydrogenase (LDH) release and resazurin reduction were regressed against total, water-soluble, and non-water-soluble metals. Pearson product–moment correlation coefficient r-values are presented. LDH release. A) Total metals. UFP, r = 0.77, p = 0.13; PM0.1–2.5, r = −0.55, p = 0.34; PM2.5–10, r = 0.32, p = 0.60; PM>10, r = −0.68, p = 0.21. B) Water-soluble metals. UFP, r = 0.51, p = 0.38; PM0.1–2.5, r = −0.64, p = 0.25; PM2.5–10, r = −0.35, p = 0.57; PM>10, r = −0.68, p = 0.20. C) Non-water-soluble metals. UFP, r = 0.75, p = 0.14; PM0.1–2.5, r = −0.46, p = 0.43; PM2.5–10, r = 0.36, p = 0.55; PM>10, r = −0.68, p = 0.21. Resazurin reduction. D) UFP, r = −0.19, p = 0.76; PM0.1–2.5, r = −0.63, p = 0.26; PM2.5–10, r = −0.60, p = 0.28; PM>10,r = 0.18, p = 0.78. Water-soluble metals. UFP, r = −0.20, p = 0.74; PM0.1–2.5, r = −0.41, p = 0.49; PM2.5–10, r = −0.09, p = 0.88; PM>10, r = 0.04, p = 0.95. Non-water-soluble metals. UFP, r = −0.12, p = 0.84; PM0.1–2.5, r = −0.65, p = 0.24; PM2.5–10, r = −0.62, p = 0.26; PM>10, r = 0.18, p = 0.77. (PDF 43 kb
Mobile and wearable computing in patagonian wilderness
Recent advances in mobile and wearable technology in the last few years have made the optimization of data collection processes possible in diverse fields.
Users currently have access to small portable devices that are not only sensitive to their activity, but also to their interaction with their environment.
These growing technological advances are in constant development , and have given way to the study and redesign of processes that can be tailored to fit any particular needs. Even users that are far from urbanization, without access to electricity can make use of these possibilities. These technologies can substantially improve their productivity, by allowing them to concentrate solely on their own tasks instead of on the interactions with the computational method used to support their activities. This study presents results and indicators relating to the application these tools within the field of Flora information retrieval, in areas far from urban centers.Instituto de Investigación en Informátic
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