Quantum Corrals, Eigenmodes and Quantum Mirages in s-wave Superconductors

We study the electronic structure of magnetic and non-magnetic quantum corrals embedded in s-wave superconductors. We demonstrate that a quantum mirage of an impurity bound state peak can be projected from the occupied into the empty focus of a non-magnetic quantum corral via the excitation of the corral's eigenmodes. We observe an enhanced coupling between magnetic impurities inside the corral, which can be varied through oscillations in the corral's impurity potential. Finally, we discuss the form of eigenmodes in magnetic quantum corrals.Comment: 4 pages, 4 figure

Ladders for Wilson Loops Beyond Leading Order

We set up a general scheme to resum ladder diagrams for the quark-anti-quark potential in N=4 super-Yang-Mills theory, and do explicit calculations at the next-to-leading order. The results perfectly agree with string theory in AdS(5)xS(5) when continued to strong coupling, in spite of a potential order-of-limits problem.Comment: 18 pages, 5 figure

Mirages and enhanced magnetic interactions in quantum corrals

We develop a theory for the interactions between magnetic impurities in nanoscopic systems. The case of impurities in quantum corrals built on the (111) Cu surface is analyzed in detail. For elliptical corrals with one impurity, clear magnetic mirages are obtained. This leads to an enhancement of the inter-impurity interactions when two impurities are placed at special points in the corral. We discuss the enhancement of the conduction electron response to the local perturbation in other nanoscopic systems.Comment: 7 pages, 5 figure

Dispositional greed and life satisfaction: the role of social comparison for well-being

The COVID-19 pandemic disrupted and reshaped effective leadership practices by introducing working-from-home protocols (WFH) and the hybrid workplace model. The current study sought to identify and understand leadership practices adopted in WFH and the transition to the hybrid model, the effectiveness of these practices, and the implications of these on future effective leadership practices in knowledge-based organizations. The current study employed an inductive thematic analysis on semi-structured interviews with thirteen senior leaders in marketing agencies and departments, grounded in causal leadership epistemology. Five themes were identified: (1) remote leadership capabilities required, (2) a soft skills leadership renaissance, (3) introspection is a coping strategy, (4), leaders' temporal quandary, and (5) hybrid leadership uncertainty. The study findings indicated the leaders who successfully coped and continued to be effective exhibited a more adaptive and resilient mindset, evolving their leadership practices and skills to suit the needs of remote (WFH) leadership. They embraced softer leadership skills and developed more humanistic leadership behaviors. They developed an introspection practice to maintain their mental and psychological balance and they mastered time management in an always-on world. This study offers leaders, managers, and employers practical insights into ongoing effective leadership practice with remote (WFH) empowered workforces and hybrid workplace normalization

Ráfagas poéticas

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Orbital-Controlled Superconductivity in f-Electron Systems

We propose a concept of superconductivity controlled by orbital degree of freedom taking CeMIn5 (M= Co, Rh, and Ir) as typical examples. A microscopic multiorbital model for CeMIn5 is analyzed by fluctuation exchange approximation. Even though the Fermi-surface structure is unchanged, the ground state is found to change significantly among paramagnetic, antiferromagnetic, and d-wave superconducting phases, depending on the dominant orbital component in the band near the Fermi energy. We show that our picture naturally explains the different low-temperature properties of CeMIn5 by carefully analyzing the crystalline electric field states.Comment: 5 pages, 4 figure

Fermion localization on degenerate and critical branes

In this work we analyze the localization of fermions on degenerate and critical Bloch branes. This is done directly on physical coordinates, in constrast to some works that has been using conformal coordinates. We find the range of coupling constants of the interaction of fermions with the scalar fields that allow us to have normalizable fermion zero-mode localized on the brane on both, critical and degenerate Bloch branes. In the case of critical branes our results agree with those found in [Class. Quantum Grav. \textbf{27} (2010) 185001]. The results on fermion localization on degenerate Bloch branes are new. We also propose a coupling of fermions to the scalar fields which leads to localization of massless fermion on both sides of a double-brane.Comment: 16 pages, 6 figure

pH plays a role in the mode of action of trimethoprim on Escherichia coli

Metabolomics-based approaches were applied to understand interactions of trimethoprim with Escherichia coli K-12 at sub-minimum inhibitory concentrations (MIC≈0.2, 0.03 and 0.003 mg L-1). Trimethoprim inhibits dihydrofolate reductase and thereby is an indirect inhibitor of nucleic acid synthesis. Due to the basicity of trimethoprim, two pH levels (5 and 7) were selected which mimicked healthy urine pH. This also allowed investigation of the effect on bacterial metabolism when trimethoprim exists in different ionization states. UHPLC-MS was employed to detect trimethoprim molecules inside the bacterial cell and this showed that at pH 7 more of the drug was recovered compared to pH 5; this correlated with classical growth curve measurements. FT-IR spectroscopy was used to establish recovery of reproducible phenotypes under all 8 conditions (3 drug levels and control in 2 pH levels) and GC-MS was used to generate global metabolic profiles. In addition to finding direct mode-of-action effects where nucleotides were decreased at pH 7 with increasing trimethoprim levels, off-target pH-related effects were observed for many amino acids. Additionally, stress-related effects were observed where the osmoprotectant trehalose was higher at increased antibiotic levels at pH 7. This correlated with glucose and fructose consumption and increase in pyruvate-related products as well as lactate and alanine. Alanine is a known regulator of sugar metabolism and this increase may be to enhance sugar consumption and thus trehalose production. These results provide a wider view of the action of trimethoprim. Metabolomics indicated alternative metabolism areas to be investigated to further understand the off-target effects of trimethoprim