Excitonic effects in the optical properties of CdSe nanowires

Using a first-principle approach beyond density functional theory we calculate the electronic and optical properties of small diameter CdSe nanowires.Our results demonstrate how some approximations commonly used in bulk systems fail at this nano-scale level and how indispensable it is to include crystal local fields and excitonic effects to predict the unique optical properties of nanowires. From our results, we then construct a simple model that describes the optical gap as a function of the diameter of the wire, that turns out to be in excellent agreement with experiments for intermediate and large diameters.Comment: submitte

Construction of the B88 exchange-energy functional in two dimensions

We construct a generalized-gradient approximation for the exchange-energy density of finite two-dimensional systems. Guided by non-empirical principles, we include the proper small-gradient limit and the proper tail for the exchange-hole potential. The observed performance is superior to that of the two-dimensional local-density approximation, which underlines the usefulness of the approach in practical applications

Notational types in scores for guitar and electronics

Notation is one of the factors upon which the longevity of mixed music is dependent. In this paper, I first discuss how academic production has conceived representation in works with electronics and dealt with inherent problems. After, I present the nine representational strategies I have identified in repertoire for guitar and electronics. These notational types aid understanding how composers conceive the interaction between the acoustic and electroacoustic parts in mixed music performance. Their simultaneous use, even if redundant, can help understanding instrumental performance issues and contribute to the preservation of the electronic part. I conclude with some considerations about the relevant strategies and their importance for the performance and permanence in the repertoire

Spin filtering in nanowire directional coupler

The spin transport characteristics of a nanowire directional electronic coupler have been evaluated theoretically via a transfer matrix approach. The application of a gate field in the region of mixing allows for control of spin current through the different leads of the coupler via the Rashba spin-orbit interaction. The combination of spin-orbit interaction and applied gate voltages on different legs of the coupler give rise to a controllable modulation of the spin polarization. Both structural factors and field strength tuning lead to a rich phenomenology that could be exploited in spintronic devices.Comment: 9 pages, 4 figure

A Giant Hand Lipoma As a Rare Cause of Secondary Carpal Tunnel Syndrome - a Case Report

Introduction: Lipomas are a rare cause of compressive neuropathy and they lead to atypical clinical presentation that can mimic carpal tunnel syndrome. Case presentation: The authors describe a rare presentation of a carpal tunnel syndrome recurrence after a hand giant lipoma, presenting with rapidly compression neuropathy of the median nerve, 6 months after de primary surgery. Discussion: Lipomas are common benign soft tumours. Their occurrence in the hand remains rare and they rarely cause secondary entrapment neuropathies. Carpal tunnel syndrome is mostly idiopathic and bilateral. Local factors should be suspected when these neuropathies present with atypical symptomatology or even when they recur after primary conventional surgical release. Investigation should consider images studies as this correct preoperative assessment leads to successful diagnosis and treatment.info:eu-repo/semantics/publishedVersio