Mass detection on mammograms: signal variations and performance changes for human and model observers

We studied the influence of signal variability on human and model observer performances for a detection task with mammographic backgrounds and computer generated clustered lumpy backgrounds (CLB). We used synthetic yet realistic masses and backgrounds that have been validated by radiologists during previous studies, ensuring conditions close to the clinical situation. Four trained non-physician observers participated in two-alternative forced-choice (2-AFC) experiments. They were asked to detect synthetic masses superimposed on real mammographic backgrounds or CLB. Separate experiments were conducted with sets of benign and malignant masses. Results under the signal-known-exactly (SKE) paradigm were compared with signal-known-statistically (SKS) experiments. In the latter case, the signal was chosen randomly for each of the 1,400 2-AFC trials (image pairs) among a set of 50 masses with similar dimensions, and the observers did not know which signal was present. Human observers' results were then compared with model observers (channelized Hotelling with Difference-of-Gaussian and Gabor channels) in the same experimental conditions. Results show that the performance of the human observers does not differ significantly when benign masses are superimposed on real images or on CLB with locally matched gray level mean and standard deviation. For both benign and malignant masses, the performance does not differ significantly between SKE and SKS experiments, when the signals' dimensions do not vary throughout the experiment. However, there is a performance drop when the SKS signals' dimensions vary from 5.5 to 9.5 mm in the same experiment. Noise level in the model observers can be adjusted to reproduce human observers' proportion of correct answers in the 2-AFC task within 5% accuracy for most condition

The Cochrane 2018 review on brief interventions in primary care for hazardous and harmful alcohol consumption: a distillation for clinicians and policy makers

Aims An updated Cochrane systematic review assessed effectiveness of screening and brief intervention to reduce hazardous or harmful alcohol consumption in general practice or emergency care settings. This paper summarises the implications of the review for clinicians. Methods Cochrane methods were followed. Reporting accords with PRISMA guidance. We searched multiple resources to September 2017, seeking randomised controlled trials of brief interventions to reduce hazardous or harmful alcohol consumption in people attending general practice, emergency care or other primary care settings for reasons other than alcohol treatment. Brief intervention was defined as a conversation comprising five or fewer sessions of brief advice or brief lifestyle counselling and a total duration of less than 60 min. Our primary outcome was alcohol consumption, measured as or convertible to grams per week. We conducted meta-analyses to assess change in consumption, and subgroup analyses to explore the impact of participant and intervention characteristics. Results We included 69 studies, of which 42 were added for this update. Most studies (88%) compared brief intervention to control. The primary meta-analysis included 34 studies and provided moderate-quality evidence that brief intervention reduced consumption compared to control after one year (mean difference −20 g/wk, 95% confidence interval −28 to −12). Subgroup analysis showed a similar effect for men and women. Conclusions Brief interventions can reduce harmful and hazardous alcohol consumption in men and women. Short, advice-based interventions may be as effective as extended, counselling-based interventions for patients with harmful levels of alcohol use who are presenting for the first time in a primary care setting

Effectiveness of brief alcohol interventions in primary care populations

© 2018 The Cochrane Collaboration. Background: Excessive drinking is a significant cause of mortality, morbidity and social problems in many countries. Brief interventions aim to reduce alcohol consumption and related harm in hazardous and harmful drinkers who are not actively seeking help for alcohol problems. Interventions usually take the form of a conversation with a primary care provider and may include feedback on the person's alcohol use, information about potential harms and benefits of reducing intake, and advice on how to reduce consumption. Discussion informs the development of a personal plan to help reduce consumption. Brief interventions can also include behaviour change or motivationally-focused counselling. This is an update of a Cochrane Review published in 2007. Objectives: To assess the effectiveness of screening and brief alcohol intervention to reduce excessive alcohol consumption in hazardous or harmful drinkers in general practice or emergency care settings. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and 12 other bibliographic databases to September 2017. We searched Alcohol and Alcohol Problems Science Database (to December 2003, after which the database was discontinued), trials registries, and websites. We carried out handsearching and checked reference lists of included studies and relevant reviews. Selection criteria: We included randomised controlled trials (RCTs) of brief interventions to reduce hazardous or harmful alcohol consumption in people attending general practice, emergency care or other primary care settings for reasons other than alcohol treatment. The comparison group was no or minimal intervention, where a measure of alcohol consumption was reported. 'Brief intervention' was defined as a conversation comprising five or fewer sessions of brief advice or brief lifestyle counselling and a total duration of less than 60 minutes. Any more was considered an extended intervention. Digital interventions were not included in this review. Data collection and analysis: We used standard methodological procedures expected by Cochrane. We carried out subgroup analyses where possible to investigate the impact of factors such as gender, age, setting (general practice versus emergency care), treatment exposure and baseline consumption. Main results: We included 69 studies that randomised a total of 33,642 participants. Of these, 42 studies were added for this update (24,057 participants). Most interventions were delivered in general practice (38 studies, 55%) or emergency care (27 studies, 39%) settings. Most studies (61 studies, 88%) compared brief intervention to minimal or no intervention. Extended interventions were compared with brief (4 studies, 6%), minimal or no intervention (7 studies, 10%). Few studies targeted particular age groups: adolescents or young adults (6 studies, 9%) and older adults (4 studies, 6%). Mean baseline alcohol consumption was 244 g/week (30.5 standard UK units) among the studies that reported these data. Main sources of bias were attrition and lack of provider or participant blinding. The primary meta-analysis included 34 studies (15,197 participants) and provided moderate-quality evidence that participants who received brief intervention consumed less alcohol than minimal or no intervention participants after one year (mean difference (MD) -20 g/week, 95% confidence interval (CI) -28 to -12). There was substantial heterogeneity among studies (I2 = 73%). A subgroup analysis by gender demonstrated that both men and women reduced alcohol consumption after receiving a brief intervention. We found moderate-quality evidence that brief alcohol interventions have little impact on frequency of binges per week (MD -0.08, 95% CI -0.14 to -0.02; 15 studies, 6946 participants); drinking days per week (MD -0.13, 95% CI -0.23 to -0.04; 11 studies, 5469 participants); or drinking intensity (-0.2 g/drinking day, 95% CI -3.1 to 2.7; 10 studies, 3128 participants). We found moderate-quality evidence of little difference in quantity of alcohol consumed when extended and no or minimal interventions were compared (-14 g/week, 95% CI -37 to 9; 6 studies, 1296 participants). There was little difference in binges per week (-0.08, 95% CI -0.28 to 0.12; 2 studies, 456 participants; moderate-quality evidence) or difference in days drinking per week (-0.45, 95% CI -0.81 to -0.09; 2 studies, 319 participants; moderate-quality evidence). Extended versus no or minimal intervention provided little impact on drinking intensity (9 g/drinking day, 95% CI -26 to 9; 1 study, 158 participants; low-quality evidence). Extended intervention had no greater impact than brief intervention on alcohol consumption, although findings were imprecise (MD 2 g/week, 95% CI -42 to 45; 3 studies, 552 participants; low-quality evidence). Numbers of binges were not reported for this comparison, but one trial suggested a possible drop in days drinking per week (-0.5, 95% CI -1.2 to 0.2; 147 participants; low-quality evidence). Results from this trial also suggested very little impact on drinking intensity (-1.7 g/drinking day, 95% CI -18.9 to 15.5; 147 participants; very low-quality evidence). Only five studies reported adverse effects (very low-quality evidence). No participants experienced any adverse effects in two studies; one study reported that the intervention increased binge drinking for women and two studies reported adverse events related to driving outcomes but concluded they were equivalent in both study arms. Sources of funding were reported by 67 studies (87%). With two exceptions, studies were funded by government institutes, research bodies or charitable foundations. One study was partly funded by a pharmaceutical company and a brewers association, another by a company developing diagnostic testing equipment. Authors' conclusions: We found moderate-quality evidence that brief interventions can reduce alcohol consumption in hazardous and harmful drinkers compared to minimal or no intervention. Longer counselling duration probably has little additional effect. Future studies should focus on identifying the components of interventions which are most closely associated with effectiveness

Probing Primordial Non-Gaussianity with Large-Scale Structure

We consider primordial non-Gaussianity due to quadratic corrections in the gravitational potential parametrized by a non-linear coupling parameter fnl. We study constraints on fnl from measurements of the galaxy bispectrum in redshift surveys. Using estimates for idealized survey geometries of the 2dF and SDSS surveys and realistic ones from SDSS mock catalogs, we show that it is possible to probe |fnl|~100, after marginalization over bias parameters. We apply our methods to the galaxy bispectrum measured from the PSCz survey, and obtain a 2sigma-constraint |fnl|< 1800. We estimate that an all sky redshift survey up to z~1 can probe |fnl|~1. We also consider the use of cluster abundance to constrain fnl and find that in order to be sensitive to |fnl|~100, cluster masses need to be determined with an accuracy of a few percent, assuming perfect knowledge of the mass function and cosmological parameters.Comment: 15 pages, 7 figure

A weakly stable algorithm for general Toeplitz systems

We show that a fast algorithm for the QR factorization of a Toeplitz or Hankel matrix A is weakly stable in the sense that R^T.R is close to A^T.A. Thus, when the algorithm is used to solve the semi-normal equations R^T.Rx = A^Tb, we obtain a weakly stable method for the solution of a nonsingular Toeplitz or Hankel linear system Ax = b. The algorithm also applies to the solution of the full-rank Toeplitz or Hankel least squares problem.Comment: 17 pages. An old Technical Report with postscript added. For further details, see http://wwwmaths.anu.edu.au/~brent/pub/pub143.htm

Planck 2015 results. XXVII. The Second Planck Catalogue of Sunyaev-Zeldovich Sources

We present the all-sky Planck catalogue of Sunyaev-Zeldovich (SZ) sources detected from the 29 month full-mission data. The catalogue (PSZ2) is the largest SZ-selected sample of galaxy clusters yet produced and the deepest all-sky catalogue of galaxy clusters. It contains 1653 detections, of which 1203 are confirmed clusters with identified counterparts in external data-sets, and is the first SZ-selected cluster survey containing > $10^3$ confirmed clusters. We present a detailed analysis of the survey selection function in terms of its completeness and statistical reliability, placing a lower limit of 83% on the purity. Using simulations, we find that the Y5R500 estimates are robust to pressure-profile variation and beam systematics, but accurate conversion to Y500 requires. the use of prior information on the cluster extent. We describe the multi-wavelength search for counterparts in ancillary data, which makes use of radio, microwave, infra-red, optical and X-ray data-sets, and which places emphasis on the robustness of the counterpart match. We discuss the physical properties of the new sample and identify a population of low-redshift X-ray under- luminous clusters revealed by SZ selection. These objects appear in optical and SZ surveys with consistent properties for their mass, but are almost absent from ROSAT X-ray selected samples

On the limits of quantum theory: contextuality and the quantum-classical cut

This paper is based on four assumptions: 1. Physical reality is made of linearly behaving components combined in non-linear ways. 2. Higher level behaviour emerges from this lower level structure. 3. The way the lower level elements behaves depends on the context in which they are imbedded. 4. Quantum theory applies to the lower level entities. An implication is that higher level effective laws, based in the outcomes of non-linear combinations of lower level linear interactions, will generically not be unitary; hence the applicability of quantum theory at higher levels is strictly limited. This leads to the view that both state vector preparation and the quantum measurement process are crucially based in top-down causal effects, and helps provide criteria for the Heisenberg cut that challenge some views on Schroedinger's cat.Comment: 65 pages, 10 diagrams. Revised in response to referee comments; to appear in Annals of Physic