PT symmetry-protected exceptional cones and analogue Hawking radiation

We show that the exceptional surfaces of linear three-dimensional non-Hermitian parity-time-symmetric two-band models attain the form of topologically stable tilted exceptional cones. By relating the exceptional cones to energy cones of two-dimensional Hermitian parity-time-symmetric two-band models, we find a connection between the exceptional cone and the light cone of an observer in the vicinity of a Schwarzschild black hole. When the cone overtilts, light-like particle-antiparticle pairs are created resembling Hawking radiation. We also investigate dissipative features of the non-Hermitian Hamiltonian related to the latter and comment on potential realizations in laboratory setups

The Analysis of Multijet Events Produced at High Energy Hadron Colliders

We define and discuss a set of (4N - 4) parameters that can be used to analyse events in which N jets have been produced in high energy hadron-hadron collisions. These multijet variables are the multijet mass and (4N - 5) independent dimensionless parameters. To illustrate the use of the variables QCD predictions are presented for events with up to five jets produced at the Fermilab Tevatron Proton-Antiproton Collider. These QCD predictions are compared with the predictions of a model in which multijet events uniformly populate the N-body phase-space

Arabidopsis mutants reveal that short- and long-term thermotolerance have different requirements for trienoic fatty acids

The photosynthetic thylakoid has the highest level of lipid unsaturation of any membrane. In Arabidopsis thaliana plants grown at 22°C, approximately 70% of the thylakoid fatty acids are trienoic – they have three double bonds. In Arabidopsis, and other species, the levels of trienoic fatty acids decline substantially at higher temperatures. Several genetic studies indicate that reduced unsaturation improves photosynthetic function and plant survival at high temperatures. Here, these studies are extended using the Arabidopsis triple mutant, fad3-2 fad7-2 fad8 that contains no detectable trienoic fatty acids. In the short-term, fluorescence analyses and electron-transport assays indicated that photosynthetic functions in this mutant are more thermotolerant than the wild type. However, long-term photosynthesis, growth, and survival of plants were all compromised in the triple mutant at high temperature. The fad3-2 fad7-2 fad8 mutant is deficient in jasmonate synthesis and this hormone has been shown to mediate some aspects of thermotolerance; however, additional experiments demonstrated that a lack of jasmonate was not a major factor in the death of triple-mutant plants at high temperature. The results indicate that long-term thermotolerance requires a basal level of trienoic fatty acids. Thus, the success of genetic and molecular approaches to increase thermotolerance by reducing membrane unsaturation will be limited by countervailing effects that compromise essential plant functions at elevated temperatures

Some Evidence on the Relevance of the Chain-reaction Theory in Selected Countries

In this paper we challenge the traditional labour market view, which argues that unemployment is determined in the long-term by its equilibrium rate, which in turn is affected by permanent shocks of some exogenous variables. In our empirical approach we decompose the dynamics of employment and labour force into transitory and permanent components. We estimated a small labour market model using VAR techniques. By simulating the model we are able to quantify the relative importance of the permanent and transitory components for the movements of the unemployment rate in four countries (Austria, France, UK, and USA). We find that the transitory component has a significant impact on unemployment only in the US. In contrast to that the permanent component appear to influence unemployment significantly in all included countries. In combination with the observation that labour market dynamics differ between countries, this may have powerful policy implications.Unemployment, Natural rate hypothesis, Labour markets, Employment, Adjustment costs

Educational level and alcohol use in adolescence and early adulthood-The role of social causation and health-related selection-The TRAILS Study

Both social causation and health-related selection may influence educational gradients in alcohol use in adolescence and young adulthood. The social causation theory implies that the social environment (e.g. at school) influences adolescents’ drinking behaviour. Conversely, the health-related selection hypothesis posits that alcohol use (along other health-related characteristics) predicts lower educational attainment. From past studies it is unclear which of these mechanisms predominates, as drinking may be both a cause and consequence of low educational attainment. Furthermore, educational gradients in alcohol use may reflect the impact of ‘third variables’ already present in childhood, such as parental socioeconomic status (SES), effortful control, and IQ. We investigated social causation and health-related selection in the development of educational gradients in alcohol use from adolescence to young adulthood in a selective educational system. We used data from a Dutch population-based cohort (TRAILS Study; n = 2,229), including measurements of educational level and drinking at ages around 14, 16, 19, 22, and 26 years (waves 2 to 6). First, we evaluated the directionality in longitudinal associations between education and drinking with cross-lagged panel models, with and without adjusting for pre-existing individual differences using fixed effects. Second, we assessed the role of childhood characteristics around age 11 (wave 1), i.e. IQ, effortful control, and parental SES, both as confounders in these associations, and as predictors of educational level and drinking around age 14 (wave 2). In fixed effects models, lower education around age 14 predicted increases in drinking around 16. From age 19 onward, we found a tendency towards opposite associations, with higher education predicting increases in alcohol use. Alcohol use was not associated with subsequent changes in education. Childhood characteristics strongly predicted education around age 14 and, to a lesser extent, early drinking. We mainly found evidence for the social causation theory in early adolescence, when lower education predicted increases in subsequent alcohol use. We found no evidence in support of the health-related selection hypothesis with respect to alcohol use. By determining initial educational level, childhood characteristics also predict subsequent trajectories in alcohol use

Topological properties of a non-Hermitian quasi-one-dimensional chain with a flat band

We investigate the spectral properties of a non-Hermitian quasi-one-dimensional lattice in two possible dimerization configurations. Specifically, we focus on a non-Hermitian diamond chain that presents a zero-energy flat band. The flat band originates from wave interference and results in eigenstates with a finite contribution only on two sites of the unit cell. To achieve the non-Hermitian characteristics, we introduce non-reciprocal intrasite hopping terms in the chain. This leads to the accumulation of eigenstates on the boundary of the system, known as the non-Hermitian skin effect. Despite this accumulation of eigenstates, for one of the two possible configurations, we can characterize the presence of non-trivial edge states at zero energy by a real-space topological invariant known as the biorthogonal polarization. We show that this invariant, evaluated using the destructive interference method, characterizes the non-trivial phase of the non-Hermitian diamond chain. For the other possible non-Hermitian configuration, we find that there is a finite quantum metric associated with the flat band. Additionally, we observe the skin effect despite having the system a purely real or imaginary spectrum. For both configurations, we show that two non- Hermitian diamond chains can be mapped into two models of the Su-Schrieffer-Heeger chains, either non-Hermitian and Hermitian, in the presence of a flat band. This mapping allows us to draw valuable insights into the behavior and properties of these systems.Comment: 14 pages, 9 figure