Comparison of superplastic forming abilities of as‐cast AZ91 magnesium alloy prepared by twin roll casting and WE43 magnesium alloy

This paper describes and compares the superplastic behaviour and microstructural evolution of twin roll cast AZ91 and WE43 rolled sheet alloys. Tests were carried out in uniaxial tension on both alloys across a range of temperatures (300 °C–525 °C) and strain rates (1?10^‐4 s^‐1–1?10^‐1 s^‐1). In the case of WE43 gas bulge testing was employed at 400 °C and 0.6 MPa to offer a better analogy to superplastic forming than uniaxial tensile testing. Elongations of over 400 % were observed within WE43 when tested at 450 °C and 1?10^‐3 s^‐1 strain rate, and over 200 % within AZ91 when tested at 350 °C and 1?10^‐3 s^‐1 strain rate. A peak cone height of 41 mm was achieved with WE43 at a temperature of 400 °C and pressure of 0.6 MPa. Electron back scattered detection technique was employed to analyse the microstructural evolution of the two alloys during the forming process. Both WE43 and AZ91 were observed to undergo dynamic recrystallization during elevated temperature tensile testing and failed at low strain rates mainly by means of coalescence of cavitation, in the case of AZ91 at high strain rates cracking of Al₁₂Mg₁₇ intermetallic particles was the dominating failure mechanism. Both alloys were seen to achieve good levels of superplastic ductility over 200 % elongation, which would be industrially useful in niche vehicle and aerospace manufacturing.     

The alleged association between induced abortion and risk of breast cancer: biology or bias?

The alleged association between induced abortion and breast cancer is one of the most controversial and important questions in women's health today. To help clinicians provide appropriate counseling, we reviewed both the primary data and review articles on this topic. We identified the studies and reviews by using Medline and the reference lists of articles and texts. We then used the U.S. Preventive Services Task Force rating system to evaluate the evidence. Many case-control studies have addressed this question, but their results have been inconsistent. Persistent problems in the case-control studies include selection of an appropriate control group, recall bias (under-reporting of induced abortion by controls), and confounding by other risk factors. Two recent, large cohort studies, which are less susceptible to bias, showed either protection or no effect on breast cancer risk from an induced abortion. At present, level II-2 evidence (cohort and case-control studies) supports a class B recommendation (fair evidence) that induced abortion does not increase a woman's risk of breast cancer later in life.     

Glass matrix/pyrochlore phase composites for nuclear wastes encapsulation

Novel composite materials have been developed as alternative forms to immobilise nuclear solid waste. These composites are made of a lead-containing glass matrix, into which particles of lanthanum zirconate pyrochlore are embedded in 10 and 30 vol% concentrations. The fabrication involves powder mixing, pressing and pressureless sintering. The processing conditions were investigated with the aim of achieving the highest possible density. The best composites obtained showed a good distribution of the lanthanum zirconate particles in the glass matrix, strong bonding of the particles to the matrix and relatively low porosity (<10%). The best sintering temperature was 600°C for the 10 vol% composite and 650°C for 30 vol%. Sintering was carried out for an hour and a heating rate of 10°C · min^–1 was shown to be superior to a heating rate of 2°C · min^–1. At the relatively low sintering temperatures used, the pyrochlore crystalline structure of lanthanum zirconate, relevant for containment of radioactive nuclei, was stable.     

Improving Password Cybersecurity Through Inexpensive and Minimally Invasive Means: Detecting and Deterring Password Reuse Through Keystroke-Dynamics Monitoring and Just-in-Time Fear Appeals

Password reuse – using the same password for multiple accounts – is a prevalent phenomenon that can make even the most secure systems vulnerable. When passwords are reused across multiple systems, hackers may compromise accounts by stealing passwords from low-security sites to access sites with higher security. Password reuse can be particularly threatening to users in developing countries in which cybersecurity training is limited, law enforcement of cybersecurity is non-existent, or in which programs to secure cyberspace are limited. This article proposes a two-pronged solution for reducing password reuse through detection and mitigation. First, based on the theories of routine, cognitive load and motor movement, we hypothesize that password reuse can be detected by monitoring characteristics of users' typing behavior (i.e. keystroke dynamics). Second, based on protection motivation theory, we hypothesize that providing just-in-time fear appeals when a violation is detected will decrease password reuse. We tested our hypotheses in an experiment and found that users' keystroke dynamics are diagnostic of password reuse. By analyzing changes in typing patterns, we were able to detect password reuse with 81.71% accuracy. We also found that just-in-time fear appeals decrease password reuse; 88.41% of users who received a fear appeal subsequently created unique passwords, whereas only 4.45% of users who did not receive a fear appeal created unique passwords. Our results suggest that future research should continue to examine keystroke dynamics as an indicator of cybersecurity behaviors and use just-in-time fear appeals as a method for reducing non-secure behavior. The findings of our research provide a practical and cost-effective solution to bolster cybersecurity through discouraging password reuse.     

Reflection-through-performance: personal implications of documenting health behaviors for the collective

Previous work has examined how technology can support health behavior monitoring in social contexts. These tools incentivize behavior documentation through the promise of virtual rewards, rich visualizations, and improved co-management of disease. Social influence is leveraged to motivate improved behaviors through friendly competition and the sharing of emotional and informational support. Prior work has described how by documenting and sharing behaviors in these tools, people engage in performances of the self. This performance happens as users selectively determine what information to share and hide, crafting a particular portrayal of their identity. Much of the prior work in this area has examined the implications of systems that encourage people to share their behaviors with friends, family, and geographically distributed strangers. In this paper, we report upon the performative nature of behavior sharing in a system created for a different social group: the local neighborhood. We designed Community Mosaic (CM), a system with a collectivistic focus: this tool asks users to document their behaviors using photographs and text, but not for their own benefit—for the benefit of others in their community. Through a 6-week deployment of CM, we evaluated the nature of behavior sharing in this system, including participants’ motivations for sharing, the way in which this sharing happened, and the reflexive impact of sharing. Our findings highlight the performative aspects of photograph staging and textual narration and how sharing this content led participants to become more aware and evaluative of their behaviors, and led them to try to eat more healthfully. We conclude with recommendations for behavior monitoring tools, specifically examining the implications of users’ perceived audience and automated behavioral tracking on opportunities for reflection-through-performance.