308 research outputs found
Lamb shift of non-degenerate energy level systems placed between two infinite parallel conducting plates
The issue of the observability of the Lamb shift in systems with
non-degenerate energy levels is put to question. To this end, we compute the
Lamb shift of such systems in the electromagnetic environment provided by two
infinite parallel conducting plates, which is instrumental in demonstrating the
existence of the so-called Casimir effect. A formula giving the relative change
in the Lamb shift (as compared to the standard one in vacuum) is explicitly
obtained for spherical semiconductor Quantum Dots (QD). It is the result of a
careful mathematical treatment of divergences in the calculations involving
distribution theory, which also settles a controversy on two different
expressions in the existing literature. It suggests a possibility of QD
non-degenerate energy spectrum fine-tuning for experimental purposes as well as
a Gedankenexperiment to observe the Lamb shift in spherical semiconductor
quantum dots.Comment: submit/040994
Recherches participatives, recherches citoyennes ... une clarification nécessaire : éditorial
Some theoretical results on semiconductor spherical quantum dots
We use an improved version of the standard effective mass approximation model
to describe quantum effects in nanometric semiconductor Quantum Dots (QDs).
This allows analytic computation of relevant quantities to a very large extent.
We obtain, as a function of the QD radius, in precise domains of validity, the
QD excitonic ground state energy and its Stark and Lamb shifts. Finally, the
Purcell effect in QDs is shown to lead to potential QD-LASER emitting in the
range of visible light
Acetabular fracture: Long-term follow-up and factors associated with secondary implantation of total hip arthroplasty
SummaryHypothesisThe present study sought to determine long-term outcome in acetabular fracture and the factors associated with secondary implantation of a total hip arthroplasty and/or with poor functional results.Material and methodsSeventy-two patients admitted between 2000 and 2005 were followed up for a maximum 11years (mean, 6.8years): 16Â females, 56Â males; mean age at injury, 41.6years (median, 40years). There were 45 simple acetabular fractures, 27 complex fractures and 27 dislocations. Late complications were: osteoarthritis (n=29), osteonecrosis of the femoral head (ONFH: n=8) and heterotopic ossification (n=2).Results and discussionTwenty-five total hip arthroplasties (THA) were performed, with a mean time to surgery of 3.7years. Associated factors for THA were: VAS (P<0.0001), PMA (P<0.0001), osteoarthritis (P<0.0001), ONFH (P<0.0002), initial dislocation (P=0.0002), no functional treatment (P=0.0014), surgical treatment (P=0.0065), initial traction (P=0.0068), anterior and posterior congruency defect (P=0.0072 and P<0.0001), and initial intra-articular foreign body (P=0.045). Factors associated with poor or bad functional results were the same, plus: etiology (P=0.0021), BMI (P=0.03) and posterior wall fracture (P=0.0325).Level of evidence4; retrospective study
Interaction de l’Als3p de Candida albicans avec les plaquettes sanguines
Date du colloque : 05/2008</p
Stark Effect of Interactive Electron-hole pairs in Spherical Semiconductor Quantum Dots
We present a theoretical variational approach, based on the effective mass
approximation (EMA), to study the quantum-confinement Stark effects for
spherical semiconducting quantum dots in the strong confinement regime of
interactive electron-hole pair and limiting weak electric field. The respective
roles of the Coulomb potential and the polarization energy are investigated in
details. Under reasonable physical assumptions, analytical calculations can be
performed. They clearly indicate that the Stark shift is a quadratic function
of the electric field amplitude in the regime of study. The resulting numerical
values are found to be in good agreement with experimental data over a
significant domain of validity
Between learning and schooling: the politics of human rights monitoring at the Universal Periodic Review
This paper explores the politics of monitoring at the Universal Periodic Review (UPR), a new United Nations human rights monitoring mechanism which aims to promote a universal approach and equal treatment when reviewing each country’s human rights situation. To what extent are these laudable aims realised, and realisable, given entrenched representations of the West and the Rest as well as geopolitical and economic inequalities both historically and in the present? Based on ethnographic fieldwork at the UN in 2010–11, the final year of the UPR’s first cycle, we explore how these aims were both pursued and subverted, paying attention to two distinct ways of talking about the UPR: first, as a learning culture in which UN member states ‘share best practice’ and engage in constructive criticism; and second, as an exam which UN member states face as students with vastly differing attitudes and competences. Accounts and experiences of diplomats from states that are not placed in the ‘good students’ category offer valuable insights into the inherent contradictions of de-historicised and de-contextualised approaches to human rights
Recognition of Candida albicans Als3 by the germ tube-specific monoclonal antibody 3D9.3
Monoclonal antibody 3D9.3 (MAb 3D9.3) reacts with the surface of Candida albicans germ tubes and recognizes a protein epitope. We used a two-step chromatography procedure to purify and identify the antigen (3D9) from C. albicans strain 66396 germ tubes. MAb 3D9.3 recognized two intense protein bands at 140 and 180 kDa. A comparative analysis between theoretical and experimental mass spectrum peaks showed that both bands corresponded to Als3. This conclusion was supported by lack of reactivity between MAb 3D9.3 and an als3Δ/als3Δ mutant strain, and the fact that an immunoglobulin preparation enriched for Als3 specificity recognized the purified 3D9 antigen. PCR demonstrated that C. albicans strain 66396 has two different-sized ALS3 alleles that correspond to the two purified protein bands. Strain- and species-specificity of the 3D9 epitope were studied with various C. albicans strains and Candida species, such as closely related Candida dubliniensis. The 3D9 epitope was detected only in C. albicans, demonstrating the utility of MAb 3D9.3 for differentiation between C. albicans and C. dubliniensis. Adhesion assays demonstrated that MAb 3D9.3 blocks adhesion of C. albicans germ tubes to human buccal epithelial cells and vascular endothelial cells
- …