Neutrinos and Thermal Leptogenesis

One of the unanswered questions of modern cosmology is the issue of baryogenesis. Why does the universe contain a huge amount of baryons but no antibaryons? What kind of a mechanism can produce this kind of an asymmetry? One theory to explain this problem is leptogenesis. In the theory right-handed neutrinos with heavy Majorana masses are added to the standard model. This addition introduces explicit lepton number violation to the theory. Instead of producing the baryon asymmetry directly, these heavy neutrinos decay in the early universe. If these decays are CP-violating, then they produce lepton number. This lepton number is then partially converted to baryon number by the electroweak sphaleron process. In this work we start by reviewing the current observational data on the amount of baryons in the universe. We also introduce Sakharov's conditions, which are the necessary criteria for any theory of baryogenesis. We review the current data on neutrino oscillation, and explain why this requires the existence of neutrino mass. We introduce the different kinds of mass terms which can be added for neutrinos, and explain how the see-saw mechanism naturally explains the observed mass scales for neutrinos motivating the addition of the Majorana mass term. After introducing leptogenesis qualitatively, we derive the Boltzmann equations governing leptogenesis, and give analytical approximations for them. Finally we review the numerical solutions for these equations, demonstrating the capability of leptogenesis to explain the observed baryon asymmetry. In the appendix simple Feynman rules are given for theories with interactions between both Dirac- and Majorana-fermions and these are applied at the tree level to calculate the parameters relevant for the theory.

A new family of multivariate heavy-tailed distributions with variable marginal amounts of tailweight: Application to robust clustering

We propose a family of multivariate heavy-tailed distributions that allow variable marginal amounts of tailweight. The originality comes from introducing multidimensional instead of univariate scale variables for the mixture of scaled Gaussian family of distributions. In contrast to most existing approaches, the derived distributions can account for a variety of shapes and have a simple tractable form with a closed-form probability density function whatever the dimension. We examine a number of properties of these distributions and illustrate them in the particular case of Pearson type VII and t tails. For these latter cases, we provide maximum likelihood estimation of the parameters and illustrate their modelling flexibility on simulated and real data clustering examples.

Rail power conditioner technology in Australian Heavy Haul Railway: A case study

Aurizon, Australia's largest freight railway operator, is investigating the use of Rail Power Conditioner (RPC) technology for load balancing, reactive power compensation and harmonic filtering. The new technology has the capability of replacing Static VAr Compensators (SVC) and Harmonic Filters, and is expected to have a significant impact on the overall costs of railway electrification. This paper presents the theoretical analysis of the real and reactive power flows in an RPC used to balance active powers in an existing V/V feeder station. This informed an RPC feasibility study undertaken at four existing Aurizon's feeder stations with V/V connected transformers.

Concentration levels of heavy metals and polycyclic aromatic hydrocarbons in car parks at Queensland University of Technology

This study investigates the level of pollutants (polycyclic aromatic hydrocarbons (PAHs) and heavy metals) in three car parks at QUT, one at Kelvin Grove campus and two at the Gardens Point campus. In addition, comparisons between site designs were assessed to identify the possible sources of heavy metals and PAHs. The main contributing source for heavy metals was identified to be from vehicle debris and emissions, while the source of PAHs was identified to be from petrol and diesel engine vehicle emissions. The highest concentration of pollutants was typically found for the 63 micro meter dust samples, proposed to be due to increased surface areas and thus available adsorption sites.

Taxonomy of factors which influence heavy metal build-up on urban road surfaces

Heavy metals build-up on urban road surfaces is a complex process and influenced by a diverse range of factors. Although numerous research studies have been conducted in the area of heavy metals build-up, limited research has been undertaken to rank these factors in terms of their influence on the build-up process. This results in limitations in the identification of the most critical factor/s for accurately estimating heavy metal loads and for designing effective stormwater treatment measures. The research study undertook an in-depth analysis of the factors which influence heavy metals build-up based on data generated from a number of different geographical locations around the world. Traffic volume was found to be the highest ranked factor in terms of influencing heavy metals build-up while land use was ranked the second. Proximity to arterial roads, antecedent dry days and road surface roughness has a relatively lower ranking. Furthermore, the study outcomes advances the conceptual understanding of heavy metals build-up based on the finding that with increasing traffic volume, total heavy metal build-up load increases while the variability decreases. The outcomes from this research study are expected to contribute to more accurate estimation of heavy metals build-up loads leading to more effective stormwater treatment design.

Influence of uncertainty inherent to heavy metal build-up and wash-off on stormwater quality

Uncertainty inherent to heavy metal build-up and wash-off stems from process variability. This results in inaccurate interpretation of stormwater quality model predictions. The research study has characterised the variability in heavy metal build-up and wash-off processes based on the temporal variations in particle-bound heavy metals commonly found on urban roads. The study outcomes found that the distribution of Al, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb were consistent over particle size fractions <150µm and >150µm, with most metals concentrated in the particle size fraction <150µm. When build-up and wash-off are considered as independent processes, the temporal variations in these processes in relation to the heavy metals load are consistent with variations in the particulate load. However, the temporal variations in the load in build-up and wash-off of heavy metals and particulates are not consistent for consecutive build-up and wash-off events that occur on a continuous timeline. These inconsistencies are attributed to interactions between heavy metals and particulates <150µm and >150µm, which are influenced by particle characteristics such as organic matter content. The behavioural variability of particles determines the variations in the heavy metals load entrained in stormwater runoff. Accordingly, the variability in build-up and wash-off of particle-bound pollutants needs to be characterised in the description of pollutant attachment to particulates in stormwater quality modelling. This will ensure the accounting of process uncertainty, and thereby enhancing the interpretation of the outcomes derived from modelling studies.

The role of moral disengagement in underage drinking and heavy episodic drinking

Objectives The current study had two aims. First, to develop a moral disengagement scale contextualized to underage drinking. Second, to investigate Bandura’s (1986) self-regulatory model within the context of underage drinking. Method Two different samples of students participated in the study. The first sample included 619 (362 females) adolescents (Mage = 15.3 years, SD = 1.09 years) and the second sample 636 (386 females) adolescents (Mage = 15.3 years, SD = 1.03 years). Students in the first sample completed the Underage Drinking Disengagement Scale (UDDS), and measures of engagement in underage drinking and heavy episodic drinking. Students in the second sample completed these measures as well as scales of general moral disengagement, personal standards and anticipatory guilt associated with underage drinking. Results For the UDDS, exploratory and confirmatory factor analyses verified a single factor structure. The UDDS was more strongly associated with engagement in underage drinking and heavy episodic drinking than a general measure of moral disengagement. A moderated mediation analysis revealed that adolescents who negatively evaluated underage drinking reported more anticipatory guilt, and more anticipatory guilt was associated with less engagement in underage drinking and less heavy episodic drinking. This relationship was weaker at high compared to low levels of underage drinking disengagement. Conclusions/Importance Understanding how adolescents self-regulate their drinking, and ways that such self-regulation may be deactivated or disengaged, may help identify those adolescents at increased risk of drinking underage and of engaging in heavy episodic drinking.

In vitro demonstration of the heavy-atom effect for photodynamic therapy

Photodynamic therapy (PDT) is an emerging treatment modality for a range of disease classes, both cancerous and noncancerous. This has brought about an active pursuit of new PDT agents that can be optimized for the unique set of photophysical characteristics that are required for a successful clinical agent. We now describe a totally new class of PDT agent, the BF2-chelated 3,5-diaryl-1H-pyrrol-2-yl-3,5-diarylpyrrol-2-ylideneamines (tetraarylazadipyrromethenes). Optimized synthetic procedures have been developed to facilitate the generation of an array of specifically substituted derivatives to demonstrate how control of key therapeutic parameters such as wavelength of maximum absorbance and singlet-oxygen generation can be achieved. Photosensitizer absorption maxima can be varied within the body's therapeutic window between 650 and 700 nm, with high extinction coefficients ranging from 75,000 to 85,000 M(-1) cm(-1). Photosensitizer singlet-oxygen generation level was modulated by the exploitation of the heavy-atom effect. An array of photosensitizers with and without bromine atom substituents gave rise to a series of compounds with varying singlet-oxygen generation profiles. X-ray structural evidence indicates that the substitution of the bromine atoms has not caused a planarity distortion of the photosensitizer. Comparative singlet-oxygen production levels of each photosensitizer versus two standards demonstrated a modulating effect on singlet-oxygen generation depending upon substituent patterns about the photosensitizer. Confocal laser scanning microscopy imaging of 18a in HeLa cervical carcinoma cells proved that the photosensitizer was exclusively localized to the cellular cytoplasm. In vitro light-induced toxicity assays in HeLa cervical carcinoma and MRC5-SV40 transformed fibroblast cancer cell lines confirmed that the heavy-atom effect is viable in a live cellular system and that it can be exploited to modulate assay efficacy. Direct comparison of the efficacy of the photosensitizers 18b and 19b, which only differ in molecular structure by the presence of two bromine atoms, illustrated an increase in efficacy of more than a 1000-fold in both cell lines. All photosensitizers have very low to nondeterminable dark toxicity in our assay system.

ERAP2 functional knockout in humans does not alter surface heavy chains or HLA-B27, inflammatory cytokines or endoplasmic reticulum stress markers

Introduction Single nucleotide polymorphisms in ERAP2 are strongly associated with ankylosing spondylitis (AS). One AS-associated single nucleotide polymorphism, rs2248374, causes a truncated ERAP2 protein that is degraded by nonsense-mediated decay. Approximately 25% of the populations of European ancestry are therefore natural ERAP2 knockouts. We investigated the effect of this associated variant on HLA class I allele presentation, surface heavy chains, endoplasmic reticulum (ER) stress markers and cytokine gene transcription in AS. Methods Patients with AS and healthy controls with either AA or GG homozygous status for rs2248374 were studied. Antibodies to CD14, CD19-ECD, HLA-A-B-C, Valpha7.2, CD161, anti-HC10 and anti-HLA-B27 were used to analyse peripheral blood mononuclear cells. Expression levels of ER stress markers (GRP78 and CHOP) and proinflammatory genes (tumour necrosis factor (TNF), IL6, IL17 and IL22) were assessed by qPCR. Results There was no significant difference in HLAclass I allele presentation or major histocompatibility class I heavy chains or ER stress markers GRP78 and CHOP or proinflammatory gene expression between genotypes for rs2248374 either between cases, between cases and controls, and between controls. Discussion Large differences were not seen in HLAB27 expression or cytokine levels between subjects with and without ERAP2 in AS cases and controls. This suggests that ERAP2 is more likely to influence AS risk through other mechanisms.

Multicarrier conduction and Boltzmann transport analysis of heavy hole mobility in HgCdTe near room temperature

Magnetotransport measurements in pulsed fields up to 15 T have been performed on mercury cadmium telluride (Hg1-xCdxTe, x similar to 0.2) bulk as well as liquid phase epitaxially grown samples to obtain the resistivity and conductivity tensors in the temperature range 220-300 K. Mobilities and densities of various carriers participating in conduction have been extracted using both conventional multicarrier fitting (MCF) and mobility spectrum analysis. The fits to experimental data, particularly at the highest magnetic fields, were substantially improved when MCF is applied to minimize errors simultaneously on both resistivity and conductivity tensors. The semiclassical Boltzmann transport equation has been solved without using adjustable parameters by incorporating the following scattering mechanisms to fit the mobility: ionized impurity, polar and nonpolar optical phonons, acoustic deformation potential, and alloy disorder. Compared to previous estimates based on the relaxation time approximation with outscattering only, polar optical scattering and ionized impurity scattering limited mobilities are shown to be larger due to the correct incorporation of the inscattering term taking into account the overlap integrals in the valence band.

Tuning the Conductance of Dirac Fermions on the Surface of a Topological Insulator

We study the transport properties of the Dirac fermions with a Fermi velocity v(F) on the surface of a topological insulator across a ferromagnetic strip providing an exchange field J over a region of width d. We show that the conductance of such a junction, in the clean limit and at low temperature, changes from oscillatory to a monotonically decreasing function of d beyond a critical J. This leads to the possible realization of a magnetic switch using these junctions. We also study the conductance of these Dirac fermions across a potential barrier of width d and potential V-0 in the presence of such a ferromagnetic strip and show that beyond a critical J, the criteria of conductance maxima changes from chi = eV(0)d/(h) over barv(F) = n pi to chi = (n + 1/2)pi for integer n. We point out that these novel phenomena have no analogs in graphene and suggest experiments which can probe them.

Human health risk assessment of heavy metals in urban stormwater

Toxic chemical pollutants such as heavy metals (HMs) are commonly present in urban stormwater. These pollutants can pose a significant risk to human health and hence a significant barrier for urban stormwater reuse. The primary aim of this study was to develop an approach for quantitatively assessing the risk to human health due to the presence of HMs in stormwater. This approach will lead to informed decision making in relation to risk management of urban stormwater reuse, enabling efficient implementation of appropriate treatment strategies. In this study, risks to human health from heavy metals were assessed as hazard index (HI) and quantified as a function of traffic and land use related parameters. Traffic and land use are the primary factors influencing heavy metal loads in the urban environment. The risks posed by heavy metals associated with total solids and fine solids (<150µm) were considered to represent the maximum and minimum risk levels, respectively. The study outcomes confirmed that Cr, Mn and Pb pose the highest risks, although these elements are generally present in low concentrations. The study also found that even though the presence of a single heavy metal does not pose a significant risk, the presence of multiple heavy metals could be detrimental to human health. These findings suggest that stormwater guidelines should consider the combined risk from multiple heavy metals rather than the threshold concentration of an individual species. Furthermore, it was found that risk to human health from heavy metals in stormwater is significantly influenced by traffic volume and the risk associated with stormwater from industrial areas is generally higher than that from commercial and residential areas.