Constrain relations for superfluid weight and pairings in a chiral flat band superconductor

Within ten years, flat band (FB) superconductivity has gained a huge interest for its remarkable features and connection to quantum geometry. We investigate the superconductivity in a FB system whose orbitals are inequivalent and in which the gap and the quantum metric are tunable. The key feature of the present theoretical study is to show a unique and simple constrain relation that pairings obey. Furthermore, pairings and superfluid weight in partially filled FB are shown to be controlled by those of the half-filled lattice. We argue that the geometry of the lattice or the complexity of the hopping terms have no impact on the features revealed in this work as far as the system is bipartite.Comment: 9 pages, 6 figure

Flat band superconductivity in a system with a tunable quantum metric : the stub lattice

Over the past years, one witnesses a growing interest in flat band (FB) physics which has become a playground for exotic phenomena. In this study, we address the FB superconductivity in onedimensional stub chain. In contrast to the sawtooth chain or the creutz ladder, for a given strength of the attractive electron-electron interaction, the stub chain allows the tuning of the real space spreading of the FB eigenstates (quantum metric or QM). We study in detail the interplay between the interaction strength and the mean value of the QM \langle g \rangle on the pairings and on the superfluid weight D_s. Our calculations reveal several interesting and intriguing features. For instance, in the weak coupling regime, D_s with respect to \langle g \rangle exhibits two different types of behaviour. Despite the fact that the pairings differs drastically, D_s scales linearly with the QM only when its \langle g \rangle is large enough (small gap limit). On the other hand, when the QM is of small amplitude an unusual power law is found, more precisely D_s \propto \langle g \rangle^\nu where \nu \longrightarrow 2 in the limit of large single particle gap. In addition to the numerical calculations, we have provided several analytical results which shed light on the physics in both the weak and strong coupling regime. Finally, we have addressed the impact of the thermal fluctuations on the superfluid weight.Comment: 9 pages, 6 figures, published in PR

Universal relations in flat band superconducting bipartite lattices

Unconventional flat band (FB) superconductivity, as observed in van der Waals heterostructures, could open promising avenues towards high-T$_c$ materials. Indeed, in FBs, pairings and superfluid weight scale linearly with the interaction parameter, such an unusual behaviour justifies strategies to promote FB engineering. Bipartite lattices (BLs) which naturally host FBs could be particularly interesting candidates. By revealing a hidden symmetry of the quasi-particle eigenstates, we demonstrate that pairings and superfluid weight obey universal relations in BLs. Remarkably, these general properties are insensitive to disorder as long as the bipartite character is protected.Comment: 5 figure

Tests on riveted joints in sheet duralumin

In making tension tests, the slippage of the joints was noted at three points across each joint. In addition, stress strain curves were obtained for plain tension specimens, and a chemical analysis was made of the sheet

Financial implications of car ownership and use: A distributional analysis based on observed spatial variance considering income and domestic energy costs

This paper presents a new perspective on assessing the financial impacts of private car usage in England and Wales using novel datasets to explore implications of motoring costs (principally Vehicle Excise Duty and road fuel costs) for households as part of the overall costs of their energy budget. Using data from an enhanced version of the Department for Transport ‘MOT’ vehicle test record database, combined with data on domestic gas and electricity consumption from the Department for Business, Energy and Industrial Strategy (formerly the Department of Energy and Climate Change), patterns of car usage and consequent energy consumption are investigated, and the costs of Vehicle Excise Duty and road fuel examined as a proportion of total expenditure on household direct energy consumption. Through the use of these new datasets it is possible to analyse how these vary spatially and in relation to levels of median income. The findings indicate that motoring costs are strongly regressive, with lower income areas, especially in rural locations, spending around twice as much of their income on motoring costs as the highest income areas

Mapping household direct energy consumption in the United Kingdom to provide a new perspective on energy justice

Targets for reductions in carbon emissions and energy use are often framed solely in terms of percentage reductions. However, the amount of energy used by households varies greatly, with some using considerably more than others and, therefore, potentially being able to make a bigger contribution towards overall reductions. Using two recently released UK datasets based on combined readings from over 70 million domestic energy meters and vehicle odometers, we present exploratory analyses of patterns of direct household energy usage. Whilst much energy justice work has previously focussed on energy vulnerability, mainly in low consumers, our findings suggest that a minority of areas appear to be placing much greater strain on energy networks and environmental systems than they need. Households in these areas are not only the most likely to be able to afford energy efficiency measures to reduce their impacts, but are also found to have other capabilities that would allow them to take action to reduce consumption (such as higher levels of income, education and particular configurations of housing type and tenure). We argue that these areas should therefore be a higher priority in the targeting of policy interventions

Personality, psychological stress, and self-reported influenza symptomatology

<p>Abstract</p> <p>Background</p> <p>Psychological stress and negative mood have been related to increased vulnerability to influenza-like illness (ILI). This prospective study re-evaluated the predictive value of perceived stress for self-reported ILI. We additionally explored the role of the negative affectivity and social inhibition traits.</p> <p>Methods</p> <p>In this study, 5,404 respondents from the general population were assessed in terms of perceived stress, personality, and control variables (vaccination, vitamin use, exercise, etc.). ILI were registered weekly using self-report measures during a follow-up period of four weeks.</p> <p>Results</p> <p>Multivariable logistic regression analysis on ILI was performed to test the predictive power of stress and personality. In this model, negative affectivity (OR = 1.05, p = 0.009), social inhibition (OR = 0.97, p = 0.011), and perceived stress (OR = 1.03, p = 0.048) predicted ILI reporting. Having a history of asthma (OR = 2.33, p = < 0.0001) was also associated with ILI reporting. Older age was associated with less self-reported ILI (OR = 0.98, P = 0.017).</p> <p>Conclusion</p> <p>Elderly and socially inhibited persons tend to report less ILI as compared to their younger and less socially inhibited counterparts. In contrast, asthma, trait negative affectivity, and perceived stress were associated with higher self-report of ILI. Our results demonstrate the importance of including trait markers in future studies examining the relation between stress and self-report symptom measures.</p

Gender and leadership aspiration:Interpersonal and collective elements of cooperative climate differentially influence women and men

Female leaders remain a minority. Because leadership aspiration is a predictor of advancement, understanding stimulating conditions is important. A neglected perspective is the impact of organizational climate. We propose that cooperative climate can engender individuals’ motivation to contribute to the organization through leadership, and that leadership aspiration of women and men is differentially sensitive to interpersonal and collective aspects of cooperative climate. We argue that women are more disposed toward relational self-construal and men toward collective self-construal, and hence women's leadership aspiration is more influenced by the interpersonal element of cooperative climate whereas men's leadership aspiration by the collective element of cooperative climate. Results of a survey of N = 404 employed men and women supported both hypotheses