You are the only possible oracle: Effective test selection for end users of interactive machine learning systems

How do you test a program when only a single user, with no expertise in software testing, is able to determine if the program is performing correctly? Such programs are common today in the form of machine-learned classifiers. We consider the problem of testing this common kind of machine-generated program when the only oracle is an end user: e.g., only you can determine if your email is properly filed. We present test selection methods that provide very good failure rates even for small test suites, and show that these methods work in both large-scale random experiments using a “gold standard” and in studies with real users. Our methods are inexpensive and largely algorithm-independent. Key to our methods is an exploitation of properties of classifiers that is not possible in traditional software testing. Our results suggest that it is plausible for time-pressured end users to interactively detect failures—even very hard-to-find failures—without wading through a large number of successful (and thus less useful) tests. We additionally show that some methods are able to find the arguably most difficult-to-detect faults of classifiers: cases where machine learning algorithms have high confidence in an incorrect result

A secondary ionization mass spectrometry calibration of Cibicidoides pachyderma Mg/Ca with temperature

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q04009, doi:10.1029/2007GC001620.An evaluation of C. pachyderma Mg/Ca using a new suite of warm water multicores from the Florida Straits shows that the slope of Mg/Ca with temperature is shallower than previously thought. Using secondary ionization mass spectrometry, we have documented that the distribution of magnesium within the polished walls of foraminiferal tests is Gaussian, suggesting that the Mg/Ca in these samples is not affected by the addition of a secondary high-magnesium calcite in the walls. The Mg/Ca within a typical C. pachyderma test varies by about ±20% (1σ/μ · 100), and the variability increases slightly in tests with higher Mg/Ca. The regression of C. pachyderma Mg/Ca with temperature has a slope of 0.13 ± 0.05 mmol mol−1 per °C, indistinguishable from the slope observed in inductively coupled plasma–mass spectrometry measurements from a different subset of the same multicores, but about one half the slope of previously published calibrations. The largest differences between the calibrations comes at the warm water end of the regression, where previously published C. pachyderma Mg/Ca values from Little Bahama Bank are at least 3 mmol mol−1 higher than observed in these new cores. The reasons for this difference are not fully known but are most likely related to diagenesis at Little Bahama Bank.This research was supported by several grants from the National Science Foundation: OCE0096469 to W.B.C. for cruise support to collect the Florida Straits cores; ATM0502428 and OCE0550271 to W. B. C. for support to obtain the Mg/Ca data on the ion probe; and OCE0425522 and OCE0550150 to T. M. for the core top calibration study using ICP-MS

Social disparities in the use of colonoscopy by primary care physicians in Ontario

<p>Abstract</p> <p>Background</p> <p>It is unclear if all persons in Ontario have equal access to colonoscopy. This research was designed to describe long-term trends in the use of colonoscopy by primary care physicians (PCPs) in Ontario, and to determine whether PCP characteristics influence the use of colonoscopy.</p> <p>Methods</p> <p>We conducted a population-based retrospective study of PCPs in Ontario between the years 1996-2005. Using administrative data we identified a screen-eligible group of patients aged 50-74 years in Ontario. These patients were linked to the PCP who provided the most continuous care to them during each year. We determined the use of any colonoscopy among these patients. We calculated the rate of colonoscopy for each PCP as the number of patients undergoing colonoscopies per 100 screen eligible patients. Negative binomial regression was used to identify factors associated with the rate of colonoscopy, using generalized estimating equations to account for clustering of patients within PCPs.</p> <p>Results</p> <p>Between 7,955 and 8,419 PCPs in Ontario per year (median age 43 years) had at least 10 eligible patients in their practices. The use of colonoscopy by PCPs increased sharply in Ontario during the study period, from a median rate of 1.51 [inter quartile range (IQR) 0.57-2.62] per 100 screen eligible patients in 1996 to 4.71 (IQR 2.70-7.53) in 2005. There was substantial variation between PCPs in their use of colonoscopy. PCPs who were Canadian medical graduates and with more years of experience were more likely to use colonoscopy after adjusting for their patient characteristics. PCPs were more likely to use colonoscopy if their patient populations were predominantly women, older, had more illnesses, and if their patients resided in less marginalized neighborhoods (lower unemployment, fewer immigrants, higher income, higher education, and higher English/French fluency).</p> <p>Conclusions</p> <p>There is substantial variation in the use of colonoscopy by PCPs, and this variation has increased as the overall use of colonoscopy increased over time. PCPs whose patients were more marginalized were less likely to use colonoscopy, suggesting that there are inequities in access.</p

New physical characterization of the Fontana Lapilli basaltic Plinian eruption, Nicaragua

The Fontana Lapilli deposit was erupted in the late Pleistocene from a vent, or multiple vents, located near Masaya volcano (Nicaragua) and is the product of one of the largest basaltic Plinian eruptions studied so far. This eruption evolved from an initial sequence of fluctuating fountain-like events and moderately explosive pulses to a sustained Plinian episode depositing fall beds of highly vesicular basaltic-andesite scoria (SiO2 > 53 wt%). Samples show unimodal grain size distribution and a moderate sorting that are uniform in time. The juvenile component predominates (> 96 wt%) and consists of vesicular clasts with both sub-angular and fluidal, elongated shapes. We obtain a maximum plume height of 32 km and an associated mass eruption rate of 1.4 × 108 kg s−1 for the Plinian phase. Estimates of erupted volume are strongly sensitive to the technique used for the calculation and to the distribution of field data. Our best estimate for the erupted volume of the majority of the climactic Plinian phase is between 2.9 and 3.8 km3 and was obtained by applying a power-law fitting technique with different integration limits. The estimated eruption duration varies between 4 and 6 h. Marine-core data confirm that the tephra thinning is better fitted by a power-law than by an exponential trend

Changes in the variability and periodicity of precipitation in Scotland

This paper analyses the temporal and spatial changes in the amount and variability of rainfall in Scotland. The sequential Mann–Kendall test reveals that total annual precipitation has increased across Scotland since the 1970s with increasing trends in variability beginning between the mid-1960s and the mid-1970s. Whilst temporally consistent increasing trends in precipitation totals prevail in the West, many weather stations in the East have experienced subsequent trend turning points in the following two decades, explaining the larger magnitude of the trends in western Scotland in recent decades. Trend analyses on six measures of rainfall variability indicate an increase in rainfall variability during the period 1961–2000, as measured by the intra-annual variance, the winter to summer precipitation ratio and the annual cumulative sum range, with decreasing trends observed in the number of dry days. Periodicities associated with the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation could explain the observed temporal variability of rainfall

Impairment of circulating endothelial progenitors in Down syndrome

<p>Abstract</p> <p>Background</p> <p>Pathological angiogenesis represents a critical issue in the progression of many diseases. Down syndrome is postulated to be a systemic anti-angiogenesis disease model, possibly due to increased expression of anti-angiogenic regulators on chromosome 21. The aim of our study was to elucidate some features of circulating endothelial progenitor cells in the context of this syndrome.</p> <p>Methods</p> <p>Circulating endothelial progenitors of Down syndrome affected individuals were isolated, <it>in vitro </it>cultured and analyzed by confocal and transmission electron microscopy. ELISA was performed to measure SDF-1α plasma levels in Down syndrome and euploid individuals. Moreover, qRT-PCR was used to quantify expression levels of <it>CXCL12 </it>gene and of its receptor in progenitor cells. The functional impairment of Down progenitors was evaluated through their susceptibility to hydroperoxide-induced oxidative stress with BODIPY assay and the major vulnerability to the infection with human pathogens. The differential expression of crucial genes in Down progenitor cells was evaluated by microarray analysis.</p> <p>Results</p> <p>We detected a marked decrease of progenitors' number in young Down individuals compared to euploid, cell size increase and some major detrimental morphological changes. Moreover, Down syndrome patients also exhibited decreased SDF-1α plasma levels and their progenitors had a reduced expression of SDF-1α encoding gene and of its membrane receptor. We further demonstrated that their progenitor cells are more susceptible to hydroperoxide-induced oxidative stress and infection with Bartonella henselae. Further, we observed that most of the differentially expressed genes belong to angiogenesis, immune response and inflammation pathways, and that infected progenitors with trisomy 21 have a more pronounced perturbation of immune response genes than infected euploid cells.</p> <p>Conclusions</p> <p>Our data provide evidences for a reduced number and altered morphology of endothelial progenitor cells in Down syndrome, also showing the higher susceptibility to oxidative stress and to pathogen infection compared to euploid cells, thereby confirming the angiogenesis and immune response deficit observed in Down syndrome individuals.</p

Pacific offshore record of plinian arc volcanism in Central America: 1. Along-arc correlations

We collected 56 marine gravity cores from the Pacific seafloor offshore Central America which contain a total of 213 volcanic ash beds. Ash-layer correlations between cores and with their parental tephras on land use stratigraphic, lithologic, and compositional criteria. In particular, we make use of our newly built database of bulk-rock, mineral, and glass major and trace element compositions of plinian and similarly widespread tephras erupted since the Pleistocene along the Central American Volcanic Arc. We thus identify the distal ashes of 11 Nicaraguan, 8 El Salvadorian, 6 Guatemalan, and 1 Costa Rican eruptions. Relatively uniform pelagic sedimentation rates allow us to determine ages of 10 previously undated tephras by their relative position between ash layers of known age. Linking the marine and terrestrial records yields a tephrostratigraphic framework for the Central American volcanic arc from Costa Rica to Guatemala. This is a useful tool and prerequisite to understand the evolution of volcanism at a whole-arc scale

The Concise Guide to PHARMACOLOGY 2023/24: G protein-coupled receptors.

peer reviewedThe Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and about 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.16177. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate