Chemistry and Distribution of Daughter Species in the Circumstellar Envelopes of O-Rich AGB Stars

Context. Thanks to the advent of Herschel and ALMA, new high-quality observations of molecules present in the circumstellar envelopes of asymptotic giant branch (AGB) stars are being reported that reveal large differences from the existing chemical models. New molecular data and more comprehensive models of the chemistry in circumstellar envelopes are now available.
Aims: The aims are to determine and study the important formation and destruction pathways in the envelopes of O-rich AGB stars and to provide more reliable predictions of abundances, column densities, and radial distributions for potentially detectable species with physical conditions applicable to the envelope surrounding IK Tau.
Methods: We use a large gas-phase chemical model of an AGB envelope including the effects of CO and N2 self-shielding in a spherical geometry and a newly compiled list of inner-circumstellar envelope parent species derived from detailed modeling and observations. We trace the dominant chemistry in the expanding envelope and investigate the chemistry as a probe for the physics of the AGB phase by studying variations of abundances with mass-loss rates and expansion velocities.
Results: We find a pattern of daughter molecules forming from the photodissociation products of parent species with contributions from ion-neutral abstraction and dissociative recombination. The chemistry in the outer zones differs from that in traditional PDRs in that photoionization of daughter species plays a significant role. With the proper treatment of self-shielding, the N → N2 and C+→ CO transitions are shifted outward by factors of 7 and 2, respectively, compared with earlier models. An upper limit on the abundance of CH4 as a parent species of (≲2.5 × 10-6 with respect to H2) is found for IK Tau, and several potentially observable molecules with relatively simple chemical links to other parent species are determined. The assumed stellar mass-loss rate, in particular, has an impact on the calculated abundances of cations and the peak-abundance radius of both cations and neutrals: as the mass-loss rate increases, the peak abundance of cations generally decreases and the peak-abundance radius of all species moves outwards. The effects of varying the envelope expansion velocity and cosmic-ray ionization rate are not as significant.

Suitability, efficiency and microbiological safety of novel physical technologies for the processing of ready-to-eat meals, meats and pumpable products

Consumer studies and market reports show an increase in consumption of ready-to-eat (RTE) foods. Although conventional processing technologies can in most cases produce safe products, they can also lead to the degradation of nutritional compounds and negatively affect quality characteristics. Consumers strongly prefer food that is minimally processed with the maximum amount of health-promoting substances. Novel processing technologies as pre- or post-treatment decontamination methods or as substitutes of conventional technologies have the potential to produce foods that are safe, rich in nutrient content and with superior organoleptic properties. Combining novel with conventional processes can eliminate potential drawbacks of novel technologies. This review examines available scientific information and critically evaluates the suitability and efficiency of various novel thermal and nonthermal technologies in terms of microbial safety, quality as well as nutrient content on the production of RTE meals, meats and pumpable products.

Towards a Cyber-physical Resilience Framework for Smart Grids

As modern power grids move towards becoming a smart grid, there is an increasing reliance on the data that is transmitted and processed by ICT systems. This reliance introduces new digital attack vectors. Many of the proposed approaches that aim to address this problem largely focus on applying well-known ICT security solutions. However, what is needed are approaches that meet the complex concerns of the smart grid as a cyber-physical system. Furthermore, to support the automatic control loops that exist in a power grid, similarly automatic security and resilience mechanisms are needed that rely on minimal operator intervention. The research proposed in this paper aims to develop a framework that ensures resilient smart grid operation in light of successful cyber-attacks.

Investigating Cyber-Physical Attacks against IEC 61850 Photovoltaic Inverter Installations

Cyber-attacks against Smart Grids have been found in the real world. Malware such as Havex and BlackEnergy have been found targeting industrial control systems (ICS) and researchers have shown that cyber-attacks can exploit vulnerabilities in widely used Smart Grid communication standards. This paper addresses a deep investigation of attacks against the manufacturing message specification of IEC 61850, which is expected to become one of the most widely used communication services in Smart Grids. We investigate how an attacker can build a custom tool to execute man-in-the-middle attacks, manipulate data, and affect the physical system. Attack capabilities are demonstrated based on NESCOR scenarios to make it possible to thoroughly test these scenarios in a real system. The goal is to help understand the potential for such attacks, and to aid the development and testing of cyber security solutions. An attack use-case is presented that focuses on the standard for power utility automation, IEC 61850 in the context of inverter-based distributed energy resource devices; especially photovoltaic (PV) generators.

RO PUF Design in FPGAs with new comparison strategies

A Physical Unclonable Function (PUF) can be used to provide authentication of devices by producing die-unique responses. In PUFs based on ring oscillators (ROs), the responses are derived from the oscillation frequencies of the ROs. However, RO PUFs can be vulnerable to attack due to the frequency distribution characteristics of the RO arrays. In this paper, in order to improve the design of RO PUFs for FPGA devices, the frequencies of RO arrays implemented on a large number of FPGA chips are statistically analyzed. Three RO frequency distribution (ROFD) characteristics are observed and discussed. Based on these ROFD characteristics, two RO comparison strategies are proposed that can be used to improve the design of RO PUFs. It is found that the symmetrical RO comparison strategy has the highest entropy density.

A Cyber-Physical Security Analysis of Synchronous-Islanded Microgrid Operation

Cyber-security research in the field of smart grids is often performed with a focus on either the power and control domain or the Information and Communications Technology (ICT) domain. The characteristics of the power equipment or ICT domain are commonly not collectively considered. This work provides an analysis of the physical effects of cyber-attacks on microgrids – a smart grid construct that allows continued power supply when disconnected from a main grid. Different types of microgrid operations are explained (connected, islanded and synchronous-islanding) and potential cyber-attacks and their physical effects are analyzed. A testbed that is based on physical power and ICT equipment is presented to validate the results in both the physical and ICT domain.

Distribution of Childhood Health Indices: Associations with Moves along the "Property Ladder"

Background
Childhood deprivation is a major risk to public health. Poor health in the early years accumulates and is expressed in adult health inequalities. The importance of social mobility - moves into and out of poverty or, indeed, change in relative affluence - for child wellbeing is less well understood. Home ownership and house value may serve as a useful measure of relative affluence and deprivation.
Method
Analysis of the Northern Ireland Longitudinal Study dataset focused on cohort members aged 18 and under at the 2001 census and their families. Using housing tenure and house value reported in 2001 and 2011, moves along the “housing ladder” over ten years were identified. Outcome measures were physical disability and mental health status as reported in 2011. Logistic regression models tested if health outcomes varied by upward and downward changes in house value.
Results
After controlling for variations in age, sex, general health and social class, mental health is worse among those who moved to a lower value house. Compared to ‘no change’, those moving from the upper quintile of house value into social renting accommodation were almost six times more likely to report poor mental health (OR 5.90 95% CI 4.52, 7.70). Conversely, those experiencing the greatest upward movement were half as likely to report poor mental health (OR 0.46 95% CI 0.31, 0.68). There were smaller associations between physical health and downward (OR 2.66 95% CI 2.16, 3.27), and upward (OR 0.75 95% CI 0.61, 0.92) moves.
Conclusion
Poor mental health is more strongly associated with declines in living standards than with improvements. The gradient appears at multiple points along this proxy affluence-deprivation spectrum, not only at the extremes. Further research should explore whether circumstances surrounding moves, or change in social position explains the differential association between the health correlates of upward versus downward mobility.