Memorable And Secure: How Do You Choose Your PIN?

Managing all your PINs is difficult. Banks acknowledge this by allowing and facilitating PIN changes. However, choosing secure PINs is a difficult task for humans as they are incapable of consciously generating randomness. This leads to certain PINs being chosen more frequently than others, which in turn increases the danger of someone else guessing correctly. We investigate different methods of supporting PIN changes and report on an evaluation of these methods in a study with 152 participants. Our contribution is twofold: We introduce an alternative to system-generated random PINs, which considers people’s preferred memorisation strategy, and, secondly, we provide indication that presenting guidance on how to avoid insecure PINs does indeed nudge people towards more secure PIN choices when they are in the process of changing their PINs

Developing and evaluating a five minute phishing awareness video

Confidence tricksters have always defrauded the unwary. The computer era has merely extended their range and made it possible for them to target anyone in the world who has an email address. Nowadays, they send phishing messages that are specially crafted to deceive. Improving user awareness has the potential to reduce their effectiveness. We have previously developed and empirically-validated phishing awareness programmes. Our programmes are specifically designed to neutralize common phish-related misconceptions and teach people how to detect phishes. Many companies and individuals are already using our programmes, but a persistent niggle has been the amount of time required to complete the awareness programme. This paper reports on how we responded by developing and evaluating a condensed phishing awareness video that delivered phishing awareness more efficiently. Having watched our video, participants in our evaluation were able to detect phishing messages significantly more reliably right after watching the video (compared to before watching the video). This ability was also demonstrated after a retention period of eight weeks after first watching the video

Oxidative capacity of the Mexico City atmosphere ? Part 1: A radical source perspective

International audienceA detailed analysis of OH, HO2 and RO2 radical sources is presented for the near field photochemical regime inside the Mexico City Metropolitan Area (MCMA). During spring of 2003 (MCMA-2003 field campaign) an extensive set of measurements was collected to quantify time resolved ROx (sum of OH, HO2, RO2) radical production rates from day- and nighttime radical sources. The Master Chemical Mechanism (MCMv3.1) was constrained by measurements of (1) concentration time-profiles of photosensitive radical precursors, i.e., nitrous acid (HONO), formaldehyde (HCHO), ozone (O3), glyoxal (CHOCHO), and other oxygenated volatile organic compounds (OVOCs); (2) respective photolysis-frequencies (J-values); (3) concentration time-profiles of alkanes, alkenes, and aromatic VOCs (103 compound are treated) and oxidants, i.e., OH- and NO3 radicals, O3; and (4) NO, NO2, meteorological and other parameters. The ROx production rate was calculated directly from these observations; MCM was used to estimate further ROx production from unconstrained sources, and express overall ROx production as OH-equivalents (i.e., taking into account the propagation efficiencies of RO2 and HO2 radicals into OH radicals). Daytime radical production is found to be about 10-25 times higher than at night; it does not track the abundance of sunlight. 12-h average daytime contributions of individual sources are: HCHO and O3 photolysis, each about 20%; O3/alkene reactions and HONO photolysis, each about 15%; unmeasured sources about 30%. While the direct contribution of O3/alkene reactions appears to be moderately small, source-apportionment of ambient HCHO and HONO identifies O3/alkene reactions as being largely responsible for jump-starting photochemistry about one hour after sunrise. The peak radical production is found to be higher than in any other urban influenced environment studied to date; further, differences exist in the timing of radical production. Our measurements and analysis comprise a database that enables testing of the representation of radical sources in photochemical models. Since the photochemical processing of pollutants is radical-limited in the MCMA, our analysis identifies the drivers for such processing. Three pathways are identified by which reductions in VOC emissions induce reductions in peak concentrations of secondary pollutants, such as O3 and secondary organic aerosol (SOA)

Exploring Consumers’ Attitudes of Smart TV Related Privacy Risks

A number of privacy risks are inherent in the Smart TV ecosystem. It is likely that many consumers are unaware of these privacy risks. Alternatively, they might be aware but consider the privacy risks acceptable. In order to explore this, we carried out an online survey with 200 participants to determine whether consumers were aware of Smart TV related privacy risks. The responses revealed a meagre level of awareness. We also explored consumers’ attitudes towards specific Smart TV related privacy risks. We isolated a number of factors that influenced rankings and used these to develop awareness-raising messages. We tested these messages in an online survey with 155 participants. The main finding was that participants were generally unwilling to disconnect their Smart TVs from the Internet because they valued the Smart TV’s Internet functionality more than their privacy. We subsequently evaluated the awareness-raising messages in a second survey with 169 participants, framing the question differently. We asked participants to choose between five different Smart TV Internet connection options, two of which retained functionality but entailed expending time and/or effort to preserve privacy

Oxidative capacity of the Mexico City atmosphere - Part 1: A radical source perspective

A detailed analysis of OH, HO2 [HO subscript 2] and RO2 [RO subscript 2] radical sources is presented for the near field photochemical regime inside the Mexico City Metropolitan Area (MCMA). During spring of 2003 (MCMA-2003 field campaign) an extensive set of measurements was collected to quantify time-resolved ROx [RO subscript x] (sum of OH, HO2 [HO subscript 2], RO2 [RO subscript 2]) radical production rates from day- and nighttime radical sources. The Master Chemical Mechanism (MCMv3.1) was constrained by measurements of (1) concentration time-profiles of photosensitive radical precursors, i.e., nitrous acid (HONO), formaldehyde (HCHO), ozone (O3 [o subscript 3]), glyoxal (CHOCHO), and other oxygenated volatile organic compounds (OVOCs); (2) respective photolysis-frequencies (J-values); (3) concentration time-profiles of alkanes, alkenes, and aromatic VOCs (103 compound are treated) and oxidants, i.e., OH- and NO3 [NO subscript 3] radicals, O3 [O subscript 3]; and (4) NO, NO2 [NO subscript 2], meteorological and other parameters. The ROx [RO subscript x] production rate was calculated directly from these observations; the MCM was used to estimate further ROx [RO subscript x] production from unconstrained sources, and express overall ROx [RO subscript x] production as OH-equivalents (i.e., taking into account the propagation efficiencies of RO2 [RO subscript 2] and HO2 [HO subscript 2] radicals into OH radicals). Daytime radical production is found to be about 10–25 times higher than at night; it does not track the abundance of sunlight. 12-h average daytime contributions of individual sources are: Oxygenated VOC other than HCHO about 33%; HCHO and O3 [O subscript 3] photolysis each about 20%; O3/alkene [O subscript 3 / alkene] reactions and HONO photolysis each about 12%, other sources <3%. Nitryl chloride photolysis could potentially contribute ~15% additional radicals, while NO2* [NO subscript 2*] + water makes – if any – a very small contribution (~2%). The peak radical production of ~7.5 107 [10 superscript 7] molec cm−3 [cm superscript -3] s−1 [s superscript -1] is found already at 10:00 a.m., i.e., more than 2.5 h before solar noon. O3/alkene [O subscript 3 / alkene] reactions are indirectly responsible for ~33% of these radicals. Our measurements and analysis comprise a database that enables testing of the representation of radical sources and radical chain reactions in photochemical models. Since the photochemical processing of pollutants in the MCMA is radical limited, our analysis identifies the drivers for ozone and SOA formation. We conclude that reductions in VOC emissions provide an efficient opportunity to reduce peak concentrations of these secondary pollutants, because (1) about 70% of radical production is linked to VOC precursors; (2) lowering the VOC/NOx [VOC / NO subscript x] ratio has the further benefit of reducing the radical re-cycling efficiency from radical chain reactions (chemical amplification of radical sources); (3) a positive feedback is identified: lowering the rate of radical production from organic precursors also reduces that from inorganic precursors, like ozone, as pollution export from the MCMA caps the amount of ozone that accumulates at a lower rate inside the MCMA. Continued VOC reductions will in the future result in decreasing peak concentrations of ozone and SOA in the MCMA.National Science Foundation (U.S.) (Grant ATM-0528227)United States. Dept. of Energy (Grant DE-FG02-0563980)Mexico. Comisión Ambiental MetropolitanaNational Science Foundation (U.S.) (CAREER grant ATM-0847793)Alliance for Global Sustainabilit

Oxidative capacity of the Mexico City atmosphere - Part 2: A ROx radical cycling perspective

A box model using measurements from the Mexico City Metropolitan Area study in the spring of 2003 (MCMA-2003) is presented to study oxidative capacity (our ability to predict OH radicals) and ROx (ROx=OH+HO2+RO2+RO) radical cycling in a polluted (i.e., very high NOx=NO+NO2) atmosphere. Model simulations were performed using the Master Chemical Mechanism (MCMv3.1) constrained with 10 min averaged measurements of major radical sources (i.e., HCHO, HONO, O3, CHOCHO, etc.), radical sink precursors (i.e., NO, NO2, SO2, CO, and 102 volatile organic compounds (VOC)), meteorological parameters (temperature, pressure, water vapor concentration, dilution), and photolysis frequencies. Modeled HOx (=OH+HO2) concentrations compare favorably with measured concentrations for most of the day; however, the model under-predicts the concentrations of radicals in the early morning. This "missing reactivity" is highest during peak photochemical activity, and is least visible in a direct comparison of HOx radical concentrations. We conclude that the most likely scenario to reconcile model predictions with observations is the existence of a currently unidentified additional source for RO2 radicals, in combination with an additional sink for HO2 radicals that does not form OH. The true uncertainty due to "missing reactivity" is apparent in parameters like chain length. We present a first attempt to calculate chain length rigorously i.e., we define two parameters that account for atmospheric complexity, and are based on (1) radical initiation, n(OH), and (2) radical termination, ω. We find very high values of n(OH) in the early morning are incompatible with our current understanding of ROx termination routes. We also observe missing reactivity in the rate of ozone production (P(O3)). For example, the integral amount of ozone produced could be under-predicted by a factor of two. We argue that this uncertainty is partly accounted for in lumped chemical codes that are optimized to predict ozone concentrations; however, these codes do not reflect the true uncertainty in oxidative capacity that is relevant to other aspects of air quality management, such as the formation of secondary organic aerosol (SOA). Our analysis highlights that apart from uncertainties in emissions, and meteorology, there is an additional major uncertainty in chemical mechanisms that affects our ability to predict ozone and SOA formation with confidence.National Science Foundation (U.S.) (ATM-0528227)United States. Dept. of Energy (Grant DE-FG02-0563980)Alliance for Global SustainabilityHenry & Camille Dreyfus FoundationAlexander von Humboldt-StiftungNational Science Foundation (U.S.) (CAREER award ATM-0847793

Revealing cytotoxic substructures in molecules using deep learning

In drug development, late stage toxicity issues of a compound are the main cause of failure in clinical trials. In silico methods are therefore of high importance to guide the early design process to reduce time, costs and animal testing. Technical advances and the ever growing amount of available toxicity data enabled machine learning, especially neural networks, to impact the field of predictive toxicology. In this study, cytotoxicity prediction, one of the earliest handles in drug discovery, is investigated using a deep learning approach trained on a highly consistent in-house data set of over 34,000 compounds with a share of less than 5% of cytotoxic molecules. The model reached a balanced accuracy of over 70%, similar to previously reported studies using Random Forest. Albeit yielding good results, neural networks are often described as a black box lacking deeper mechanistic understanding of the underlying model. To overcome this absence of interpretability, a Deep Taylor Decomposition method is investigated to identify substructures that may be responsible for the cytotoxic effects, the so-called toxicophores. Furthermore, this study introduces cytotoxicity maps which provide a visual structural interpretation of the relevance of these substructures. Using this approach could be helpful in drug development to predict the potential toxicity of a compound as well as to generate new insights into the toxic mechanism. Moreover, it could also help to de-risk and optimize compounds

Characterizing ozone production in the Mexico City Metropolitan Area: a case study using a chemical transport model

International audienceAn episodic simulation is conducted to characterize ozone (O3) photochemical production and investigate its sensitivity to emission changes of ozone precursors in the Mexico City Metropolitan Area (MCMA) using the Comprehensive Air Quality Model with extensions (CAMx). High Ox (O3+NO2) photochemical production rates of 10?80 ppb/h are predicted due to the high reactivity of volatile organic compounds (VOCs) in which alkanes, alkenes, and aromatics exert comparable contributions. The predicted ozone production efficiency is between 4?10 O3 molecules per NOx molecule oxidized, and increases with VOC-to-NO2 reactivity ratio. Process apportionment analyses indicate significant outflow of pollutants such as O3 and peroxyacetyl nitrate (PAN) from the urban area to the surrounding regional environment. PAN is not in chemical-thermal equilibrium during the photochemically active periods. Sensitivity studies of O3 production suggest that O3 formation in the MCMA urban region with less chemical aging (NOz/NOy3 production and its sensitivities to precursors suggest that midday O3 formation during this episode is VOC sensitive in the urban region on the basis of the current emissions inventory. More episodic studies are needed to construct a comprehensive and representative picture of the O3 production characteristics and its response to emission controls

Characterizing ozone production and response under different meteorological conditions in Mexico City

International audienceTropospheric photochemistry, particularly the formation of ozone (O3), depends not only on pollutant emissions, but also on meteorological conditions. In this study a 3-D chemical transport model CAMx was employed to investigate the O3 formation and its response to emission reductions under three distinctively different meteorological conditions ("Cold Surge", "O3-North" and "O3-South") in the Mexico City Metropolitan Area during the MCMA-2003 field measurement campaign. The O3 formation characteristics and sensitivity to emissions changes were found to be weakly dependent on the meteorological conditions. The evolution of O3 formation and sensitivity were also examined along the photochemical plume transport pathway. The midday O3 production was found to undergo a rapid increase in a narrow range of chemical aging, while plumes in the downwind were characterized with low and constant O3 production, and plumes along their transport pathway were featured by a combination of the two. The O3 formation was more VOC sensitive near the source area, but as the plume became chemically aged, O3 formation became progressively VOC insensitive and more NOx sensitive

The influence of natural and anthropogenic secondary sources on the glyoxal global distribution

Glyoxal, the smallest dicarbonyl, which has recently been observed from space, is expected to provide indications on volatile organic compounds (VOC) oxidation and secondary aerosol formation in the troposphere. Glyoxal (CHOCHO) is known to be mostly of natural origin and is produced during biogenic VOC oxidation. However, a number of anthropogenically emitted hydrocarbons, like acetylene and aromatics, have been positively identified as CHOCHO precursors. The present study investigates the contribution of pollution to the CHOCHO levels by taking into account the secondary chemical formation of CHOCHO from precursors emitted from biogenic, anthropogenic and biomass burning sources. The impact of potential primary land emissions of CHOCHO is also investigated. A global 3-dimensional chemistry transport model of the troposphere (TM4-ECPL) able to simulate the gas phase chemistry coupled with all major aerosol components is used. &lt;br&gt;&lt;br&gt; The secondary anthropogenic contribution from fossil fuel and industrial VOCs emissions oxidation to the CHOCHO columns is found to reach 20–70% in the industrialized areas of the Northern Hemisphere and 3–20% in the tropics. This secondary CHOCHO source is on average three times larger than that from oxidation of VOCs from biomass burning sources. The chemical production of CHOCHO is calculated to equal to about 56 Tg y&lt;sup&gt;&amp;minus;1&lt;/sup&gt; with 70% being produced from biogenic hydrocarbons oxidation, 17% from acetylene, 11% from aromatic chemistry and 2% from ethene and propene. CHOCHO is destroyed in the troposphere primarily by reaction with OH radicals (23%) and by photolysis (63%), but it is also removed from the atmosphere through wet (8%) and dry deposition (6%). Potential formation of secondary organic aerosol through CHOCHO losses on/in aerosols and clouds is neglected here due to the significant uncertainties associated with the underlying chemistry. The global annual mean CHOCHO burden and lifetime in the model domain are estimated to be 0.02 Tg (equal to the global burden seen by SCIAMACHY over land for the year 2005) and about 3 h, respectively. The model results are compared with satellite observations of CHOCHO columns. When accounting only for the secondary sources of CHOCHO in the model, the model underestimates CHOCHO columns observed by satellites. This is attributed to an overestimate of CHOCHO sinks or a missing global source of about 20 Tg y&lt;sup&gt;&amp;minus;1&lt;/sup&gt;. Using the current primary emissions of CHOCHO from biomass burning together with the anthropogenic combustion sources of about 7 Tg y&lt;sup&gt;&amp;minus;1&lt;/sup&gt; leads to an overestimate by the model over hot spot areas