Risks of Offline Verify PIN on Contactless Cards

Contactless card payments are being introduced around the world al- lowing customers to use a card to pay for small purchases by simply placing the card onto the Point of Sale terminal. Contactless transactions do not require veri- fication of the cardholder’s PIN. However our research has found the redundant verify PIN functionality is present on the most commonly issued contactless credit and debit cards currently in circulation in the UK. This paper presents a plausible attack scenario which exploits contactless verify PIN to give unlimited attempts to guess the cardholder’s PIN without their knowledge. It also gives experimental data to demonstrate the practical viability of the attack as well as references to support our argument that contactless verify PIN is redundant functionality which compromises the security of payment cards and the cardholder

Can k-NN imputation improve the performance of C4.5 with small software project data sets? A comparative evaluation

Missing data is a widespread problem that can affect the ability to use data to construct effective prediction systems. We investigate a common machine learning technique that can tolerate missing values, namely C4.5, to predict cost using six real world software project databases. We analyze the predictive performance after using the k-NN missing data imputation technique to see if it is better to tolerate missing data or to try to impute missing values and then apply the C4.5 algorithm. For the investigation, we simulated three missingness mechanisms, three missing data patterns, and five missing data percentages. We found that the k-NN imputation can improve the prediction accuracy of C4.5. At the same time, both C4.5 and k-NN are little affected by the missingness mechanism, but that the missing data pattern and the missing data percentage have a strong negative impact upon prediction (or imputation) accuracy particularly if the missing data percentage exceeds 40%

Grindr Users Take More Risks, but Are More Open to Human Immunodeficiency Virus (HIV) Pre-exposure Prophylaxis: Could This Dating App Provide a Platform for HIV Prevention Outreach?

BackgroundTechnology has changed the way that men who have sex with men (MSM) seek sex. More than 60% of MSM in the United States use the internet and/or smartphone-based geospatial networking apps to find sex partners. We correlated use of the most popular app (Grindr) with sexual risk and prevention behavior among MSM.MethodsA nested cohort study was conducted between September 2018 and June 2019 among MSM receiving community-based human immunodeficiency virus (HIV) and sexually transmitted infection (STI) screening in central San Diego. During the testing encounter, participants were surveyed for demographics, substance use, risk behavior (previous 3 months), HIV pre-exposure prophylaxis (PrEP) use, and Grindr usage. Participants who tested negative for HIV and who were not on PrEP were offered immediate PrEP.ResultsThe study included 1256 MSM, 1090 of whom (86.8%) were not taking PrEP. Overall, 580 of 1256 (46%) participants indicated that they used Grindr in the previous 7 days. Grindr users reported significantly higher risk behavior (greater number of male partners and condomless sex) and were more likely to test positive for chlamydia or gonorrhea (8.6% vs 4.7% of nonusers; P = .005). Grindr users were also more likely to be on PrEP (18.7% vs 8.7% of nonusers; P < .001) and had fewer newly diagnosed HIV infections (9 vs 26 among nonusers; P = .014). Grindr users were also nearly twice as likely as nonusers to initiate PrEP (24.6% vs 14%; P < .001).ConclusionsGiven the higher risk behavior and greater acceptance of PrEP among MSM who used Grindr, Grindr may provide a useful platform to promote HIV and STI testing and increase PrEP uptake

Innovation in the Construction and Property Management Industries

Purpose – The purpose of this practice paper is to examine how the Knowledge Transfer Partnership (KTP) scheme has been employed to introduce change and deliver business benefit in the construction industry. Design/methodology/approach – The paper begins with an introduction to the KTP scheme and its context within the University of Gloucestershire which serves as an introduction to three case studies, each one covering a 21‐24 month time span. The cases draw their empirical material from the experience of managing the KTPs, interviews, meeting minutes, board papers and final reports. Findings – All three case studies have been successful in the introduction of new thinking or new ways of working in different areas of business. In one case study, a new marketing strategy was developed and implemented; in another, a new consultancy capability has been developed and embedded in the company; and in the third, new information systems were introduced to support corporate growth. Originality/value – The value of the case studies lies in their originality and the paper highlights the value of the KTP scheme as a catalyst for the introduction of new ideas and initiatives in three different sectors of the construction industry. The paper also illustrates how academics can work productively in a commercial environment with industry partner

Innovation in the Construction and Property Management Industries

Purpose – The purpose of this practice paper is to examine how the Knowledge Transfer Partnership (KTP) scheme has been employed to introduce change and deliver business benefit in the construction industry. Design/methodology/approach – The paper begins with an introduction to the KTP scheme and its context within the University of Gloucestershire which serves as an introduction to three case studies, each one covering a 21‐24 month time span. The cases draw their empirical material from the experience of managing the KTPs, interviews, meeting minutes, board papers and final reports. Findings – All three case studies have been successful in the introduction of new thinking or new ways of working in different areas of business. In one case study, a new marketing strategy was developed and implemented; in another, a new consultancy capability has been developed and embedded in the company; and in the third, new information systems were introduced to support corporate growth. Originality/value – The value of the case studies lies in their originality and the paper highlights the value of the KTP scheme as a catalyst for the introduction of new ideas and initiatives in three different sectors of the construction industry. The paper also illustrates how academics can work productively in a commercial environment with industry partner

Warm Dark Matter versus Bumpy Power Spectra

In this paper we are exploring the differences between a Warm Dark Matter model and a CDM model where the power on a certain scale is reduced by introducing a narrow negative feature ("dip"). This dip is placed in a way so as to mimic the loss of power in the WDM model: both models have the same integrated power out to the scale where the power of the Dip model rises to the level of the unperturbed CDM spectrum again. Using N-body simulations we show that some of the large-scale clustering patterns of this new model follow more closely the usual CDM scenario while simultaneously suppressing small scale structures (within galactic halos) even more efficiently than WDM. The analysis in the paper shows that the new Dip model appears to be a viable alternative to WDM but it is based on different physics. Where WDM requires the introduction of a new particle species the Dip model is based on a non-standard inflationary period. If we are looking for an alternative to the currently challenged standard LCDM structure formation scenario, neither the LWDM nor the new Dip model can be ruled out based on the analysis presented in this paper. They both make very similar predictions and the degeneracy between them can only be broken with observations yet to come.Comment: 7 pages, 8 figures, replaced with MNRAS accepted version (minor revisions), high-resolution figures at http://astronomy.swin.edu.au/staff/aknebe

Synchronous versus sequential updating in the three-state Ising neural network with variable dilution

The three-state Ising neural network with synchronous updating and variable dilution is discussed starting from the appropriate Hamiltonians. The thermodynamic and retrieval properties are examined using replica mean-field theory. Capacity-temperature phase diagrams are derived for several values of the pattern activity and different gradations of dilution, and the information content is calculated. The results are compared with those for sequential updating. The effect of self-coupling is established. Also the dynamics is studied using the generating function technique for both synchronous and sequential updating. Typical flow diagrams for the overlap order parameter are presented. The differences with the signal-to-noise approach are outlined.Comment: 21 pages Latex, 12 eps figures and 1 ps figur

HI and CO in the circumstellar environment of the oxygen-rich AGB star RX Lep

Circumstellar shells around AGB stars are built over long periods of time that may reach several million years. They may therefore be extended over large sizes (~1 pc, possibly more), and different complementary tracers are needed to describe their global properties. In the present work, we combined 21-cm HI and CO rotational line data obtained on an oxygen-rich semi-regular variable, RX Lep, to describe the global properties of its circumstellar environment. With the SEST, we detected the CO(2-1) rotational line from RX Lep. The line profile is parabolic and implies an expansion velocity of ~4.2 km/s and a mass-loss rate ~1.7 10^-7 Msun/yr (d = 137 pc). The HI line at 21 cm was detected with the Nancay Radiotelescope on the star position and at several offset positions. The linear shell size is relatively small, ~0.1 pc, but we detect a trail extending southward to ~0.5 pc. The line profiles are approximately Gaussian with an FWHM ~3.8 km/s and interpreted with a model developed for the detached shell around the carbon-rich AGB star Y CVn. Our HI spectra are well-reproduced by assuming a constant outflow (Mloss = 1.65 10^-7 Msun/yr) of ~4 10^4 years duration, which has been slowed down by the external medium. The spatial offset of the HI source is consistent with the northward direction of the proper motion, lending support to the presence of a trail resulting from the motion of the source through the ISM, as already suggested for Mira, RS Cnc, and other sources detected in HI. The source was also observed in SiO (3 mm) and OH (18 cm), but not detected. The properties of the external parts of circumstellar shells around AGB stars should be dominated by the interaction between stellar outflows and external matter for oxygen-rich, as well as for carbon-rich, sources, and the 21-cm HI line provides a very useful tracer of these regions.Comment: 15 pages, 9 figures, accepted for publication in A&

The Masses of the Milky Way and Andromeda galaxies

We present a family of robust tracer mass estimators to compute the enclosed mass of galaxy haloes from samples of discrete positional and kinematical data of tracers, such as halo stars, globular clusters and dwarf satellites. The data may be projected positions, distances, line of sight velocities or proper motions. Forms of the estimator tailored for the Milky Way galaxy and for M31 are given. Monte Carlo simulations are used to quantify the uncertainty as a function of sample size. For the Milky Way, the satellite sample consists of 26 galaxies with line-of-sight velocities. We find that the mass of the Milky Way within 300 kpc is ~ 0.9 x 10^12 solar masses assuming velocity isotropy. However, the mass estimate is sensitive to the anisotropy and could plausibly lie between 0.7 - 3.4 x 10^12 solar masses. Incorporating the proper motions of 6 Milky Way satellites into the dataset, we find ~ 1.4 x 10^12 solar masses. The range here if plausible anisotropies are used is still broader, from 1.2 - 2.7 x 10^12 solar masses. For M31, there are 23 satellite galaxies with measured line-of-sight velocities, but only M33 and IC 10 have proper motions. We use the line of sight velocities and distances of the satellite galaxies to estimate the mass of M31 within 300 kpc as ~ 1.4 x 10^12 solar masses assuming isotropy. There is only a modest dependence on anisotropy, with the mass varying between 1.3 -1.6 x 10^12 solar masses. Given the uncertainties, we conclude that the satellite data by themselves yield no reliable insights into which of the two galaxies is actually the more massive.Comment: 15 pages, submitted to MNRA