The Need, Benefits, and Demonstration of a Minimization Principle for Excited States

It is shown that the standard methods of computing excited states in truncated spaces must yield wave functions that, beyond truncation, are in principle veered away from the exact, and a remedy is demonstrated via a presented functional, F$_n$, obeying a minimization principle for excited states. It is further demonstrated that near avoided crossings, between two MCSCF 'flipped roots' the wave function that leads to the excited state has the lowest F$_n$.Comment: 4 pages, 1 figure, International Conference of Computational Methods in Sciences and Engineering - 2015 / Computational Chemistry, 20-23 March 2015, Athens, GREEC

Variational Functionals for Excited States

Functionals that have local minima at the excited states of a non degenerate Hamiltonian are presented. Then, improved mutually orthogonal approximants of the ground and the first excited state are reported.Comment: 4 page

Gender in the Construction Industry: Literature Review and Comparative Survey of Men’s and Women’s Perceptions in UK Construction Consultancies

For more than two decades, construction industry leaders have made attempts to attract more women into professional roles to ease skills shortages and diversify the workforce. However, the number of women working in the industry has not improved significantly. This paper reviews previous literature on gender diversity in the construction industry and disseminates findings from a survey that investigated whether there are significant differences in self-perception between men and women in construction consultancies operating in the United Kingdom (UK). The survey questionnaire was completed by 60 men and 57 women. Analysis of the results confirmed that women tend to follow “zig-zag” career development paths and that “global self-worth” of women over the age of 40 is the lowest among all ages. However, little variation was found on initiatives to improve retention of women in construction consultancies. The results reveal that both men and women regarded improved flexible working-arrangements, transparent promotion criteria, return-to-work training, and outreach programs to schools the most crucial initiatives to retain women. This reinforces the call for organizations to introduce innovative strategic plans to change the masculine culture of the construction profession and modernize working practice away from the existing rather outdated traditional structure

Integrated model for the stressors, stress, stress-coping behaviour of construction project managers in the UK

Purpose It is axiomatic that construction is a fast-paced and competitive industry, which goes hand in hand with many construction professionals suffering from stress including construction project managers (C-PMs). The role of C-PMs is crucial to achieving project success as they are responsible for planning the project, organising human resources, controlling operations and the budget, and forecasting probable difficulties. The purpose of this paper is to investigate the causal relationships between stressors, stresses, stress-coping behaviours and their impact on the performance of C-PMs. Design/methodology/approach To investigate the relationships between stress and performance among C-PMs, a questionnaire was designed based on the extensive literature, and was sent to 150 C-PMs who had amassed at least five years’ direct working experience in the construction industry. A total of 44 completed questionnaires were returned. Correlation analysis and structural equation modelling were employed to understand the integrated relationships between these factors. Based on the data collected and analysis of the results, an integrated structural equation model of the stresses and performances of C-PMs was developed using AMOS version 22.0. Findings The results of structural equation modelling reveal the following: burnout is the type of stress that has the highest impact on the performance of C-PMs, being detrimental to their interpersonal performance (IPP) and positive for their organisational performance (OP), whereas physiological stress worsens the task performance of C-PMs and objective stress improves their IPP. The most active stressor towards the performance of C-PMs is “workgroup cooperation”, which has an impact on the IPP in a positive way but is detrimental to the OP. Career-developing environment, poor organisational structure and role conflict affect both stress and performance together. Originality/value This study provides a comprehensive investigation into the impact of various types of stress on the performances of C-PMs. The result constitutes a significant step towards the stress management of C-PMs in the dynamic and stressful construction industry

Magnon Exchange Mechanism of Ferromagnetic Superconductivity

The magnon exchange mechanism of ferromagnetic superconductivity (FM-superconductivity) was developed to explain in a natural way the fact that the superconductivity in $UGe_2$, $ZrZn_2$ and $URhGe$ is confined to the ferromagnetic phase.The order parameter is a spin anti-parallel component of a spin-1 triplet with zero spin projection. The transverse spin fluctuations are pair forming and the longitudinal ones are pair breaking. In the present paper, a superconducting solution, based on the magnon exchange mechanism, is obtained which closely matches the experiments with $ZrZn_2$ and $URhGe$. The onset of superconductivity leads to the appearance of complicated Fermi surfaces in the spin up and spin down momentum distribution functions. Each of them consist of two pieces, but they are simple-connected and can be made very small by varying the microscopic parameters. As a result, it is obtained that the specific heat depends on the temperature linearly, at low temperature, and the coefficient $\gamma=\frac {C}{T}$ is smaller in the superconducting phase than in the ferromagnetic one. The absence of a quantum transition from ferromagnetism to ferromagnetic superconductivity in a weak ferromagnets $ZrZn_2$ and $URhGe$ is explained accounting for the contribution of magnon self-interaction to the spin fluctuations' parameters. It is shown that in the presence of an external magnetic field the system undergoes a first order quantum phase transition.Comment: 9 pages, 7 figures, accepted for publication in Phys.Rev.

Numerical simulation of flow and contaminant migration at a municipal landfill

The flow and transport characteristics of the Ano Liosia Landfill site i

Magnon-Paramagnon Effective Theory of Itinerant Ferromagnets

The present work is devoted to the derivation of an effective magnon-paramagnon theory starting from a microscopic lattice model of ferromagnetic metals. For some values of the microscopic parameters it reproduces the Heisenberg theory of localized spins. For small magnetization the effective model describes the physics of weak ferromagnets in accordance with the experimental results. It is written in a way which keeps O(3) symmetry manifest,and describes both the order and disordered phases of the system. Analytical expression for the Curie temperature,which takes the magnon fluctuations into account exactly, is obtained. For weak ferromagnets $T_c$ is well below the Stoner's critical temperature and the critical temperature obtained within Moriya's theory.Comment: 14 pages, changed content,new result

Depth versus surface: A critical review of subdural and depth electrodes in intracranial electroencephalographic studies

Intracranial electroencephalographic (IEEG) recording, using subdural electrodes (SDEs) and stereoelectroencephalography (SEEG), plays a pivotal role in localizing the epileptogenic zone (EZ). SDEs, employed for superficial cortical seizure foci localization, provide information on two-dimensional seizure onset and propagation. In contrast, SEEG, with its three-dimensional sampling, allows exploration of deep brain structures, sulcal folds, and bihemispheric networks. SEEG offers the advantages of fewer complications, better tolerability, and coverage of sulci. Although both modalities allow electrical stimulation, SDE mapping can tessellate cortical gyri, providing the opportunity for a tailored resection. With SEEG, both superficial gyri and deep sulci can be stimulated, and there is a lower risk of afterdischarges and stimulation-induced seizures. Most systematic reviews and meta-analyses have addressed the comparative effectiveness of SDEs and SEEG in localizing the EZ and achieving seizure freedom, although discrepancies persist in the literature. The combination of SDEs and SEEG could potentially overcome the limitations inherent to each technique individually, better delineating seizure foci. This review describes the strengths and limitations of SDE and SEEG recordings, highlighting their unique indications in seizure localization, as evidenced by recent publications. Addressing controversies in the perceived usefulness of the two techniques offers insights that can aid in selecting the most suitable IEEG in clinical practice