Electrons in a square lattice

“Electrons in a square lattice” describes how a two-dimensional square lattice gives a helpful case intermediate between one dimension and the complication of three dimensions. The “empty lattice” divides up k-space into Brillouin zones in anticipation of a periodic potential whose period is given but whose magnitude is at this stage zero. A wooden model uses height to represent energy. Rearranging the model's pieces into the reduced-zone scheme displays how electrons can have surprising energy–wavevector relations, including overlapping bands, anisotropic effective masses, and indirect band gaps.

How price moderates assessments of coffee quality across profiles of gender and experience

Proceeding from studies that identify the extrinsic price cue as a mediator between a product’s perceived and intrinsic merit, we report on a blind-versus-sighted coffee tasting experiment conducted to determine the impact of the price-cue across coffee-user categories of gender and relative experience. Seven instant coffees were tasted by 100 subjects producing 700 paired blind and sighted tastings. Aggregating the data, OLS regression models were run to estimate price-effects across discrete and overlapping bands of gender and self-confessed expertise (non-expert and expert). Our analysis reveals the extent to which price-effects demean a coffee’s intrinsic merit during sighted tastings, with experienced male coffee drinkers most especially susceptible to price persuasion, and less experienced female drinkers the least. Thus our paper introduces a cheap and affective means of testing for such cue-effects. Neuromarketing styles of testing are usually cumbersome, expensive and difficult to scale. The method show-cased here offers a meaningful alternative. These findings uphold the view that the price cue remains a critical tool in the marketing of coffee; most notably because of its potential cost-free contribution to the ramping of experienced pleasure without any augmentation of quality. Further implications are explored.

A Multiband Model for LaO1-xFxFeAs

Based on electronic structure calculations using WIEN2k code for the iron oxypnictide LaO1-xFxFeAs a multi-band model is proposed. Within the BCS framework a generalized Fermi surface with overlapping bands is introduced. s-wave pairing symmetry and different doping values are considered. This model is used to describe some properties of iron-based oxypnictide superconductors as function of the coupling parameter as well as other relevant parameters of the model. In order to get numerical results the experimental data of LaO1-xFxFeAs with several doping concentrations provide the input of this work.

F 1s spectroscopy and ionic fragmentation of trifluoropropyne

The F 1s excitation spectroscopy and ionic fragmentation of 3,3,3-trifluoro-1-propyne have been studied using synchrotron radiation and ion time-of-flight mass spectrometry. The total ion yield spectrum and photoionization branching ratios in the vicinity of the F 1s ionization threshold are reported. Core excited state calculations using the static exchange approximation are used to aid in the interpretation of the experimental results. The F 1s excitation spectrum consists of a number of broad overlapping bands below threshold, attributed to excitations to mixed σ*(C-F)/π*(C-C) molecular orbitals and unresolved Rydberg states, and a continuum shape resonance 12.5 eV above threshold. Ionic fragmentation following F 1s excitation or ionization results overwhelmingly in singly charged ionic fragments, primarily via cleavage of bonds to the fluorinated carbon atom adjacent to the core-excited atom.Key words: F 1s excitation, XANES, photoelectron-photoion coincidence, ionic fragmentation, static exchange approximation.