Bright Polarized Single-Photon Source Based on a Linear Dipole.

Semiconductor quantum dots in cavities are promising single-photon sources. Here, we present a path to deterministic operation, by harnessing the intrinsic linear dipole in a neutral quantum dot via phonon-assisted excitation. This enables emission of fully polarized single photons, with a measured degree of linear polarization up to 0.994±0.007, and high population inversion-85% as high as resonant excitation. We demonstrate a single-photon source with a polarized first lens brightness of 0.50±0.01, a single-photon purity of 0.954±0.001, and single-photon indistinguishability of 0.909±0.004.

Hong-Ou-Mandel Interference with Imperfect Single Photon Sources.

Hong-Ou-Mandel interference is a cornerstone of optical quantum technologies. We explore both theoretically and experimentally how unwanted multiphoton components of single-photon sources affect the interference visibility, and find that the overlap between the single photons and the noise photons significantly impacts the interference. We apply our approach to quantum dot single-photon sources to access the mean wave packet overlap of the single-photon component. This study provides a consistent platform with which to diagnose the limitations of current single-photon sources on the route towards the ideal device.

Perceived barriers to and facilitators of physical activity in people with knee osteoarthritis: Development of the Evaluation of the Perception of Physical Activity questionnaire.

BACKGROUND: The physical activity (PA) level of individuals with knee osteoarthritis is lower than in the general population. International recommendations recommend a non-pharmacological intervention including a self-management education program, weight loss and an adapted exercise program. However, we have no scale assessing the perceived barriers to and facilitators of PA in this population. OBJECTIVE: We constructed and validated a self-administered questionnaire assessing perceived barriers to and facilitators of regular practice of PA in people with knee osteoarthritis. METHODS: Semi-structured interviews identified 24 barriers and facilitators. We developed a 24-item questionnaire, Evaluation of the Perception of Physical Activity (EPPA) that was completed by 548 individuals with knee osteoarthritis, to assess acceptability, construct validity, internal consistency and convergent validity. Participants also completed the Knee Osteoarthritis Fears and Beliefs Questionnaire (KOFBeQ), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and International Physical Activity Questionnaire (IPAQ). Reliability and sensitivity to change were evaluated in a second group of 168 people with knee osteoarthritis at a 3-week spa therapy resort. RESULTS: Factorial analysis identified 17 items grouped into 4 subscales (Barriers, Facilitators, Motivation and Beliefs). The internal consistency was good for Barriers, Facilitators and Motivation subscales (Cronbach α>0.70) and intermediate for the Beliefs subscale (Cronbach α=0.64). The EPPA subscale scores were significantly correlated with KOFBeQ and WOMAC scores but not associated with IPAQ physical activity level. Reliability was good for all subscales, with intraclass correlation coefficients>0.60. A sensitivity to change was found for only the Beliefs subscale, with a moderate effect size. CONCLUSIONS: The EPPA questionnaire has good psychometric properties and can help guide the management of knee osteoarthritis. It can be used in research for evaluating the perception of physical activity.

Contribution made by multivariate curve resolution applied to gel permeation chromatography-Fourier transform infrared data for an in-depth characterization of styrene-butadiene rubber blends.

We evaluate the contribution made by multivariate curve resolution-alternating least squares (MCR-ALS) for resolving gel permeation chromatography-Fourier transform infrared (GPC-FT-IR) data collected on butadiene rubber (BR) and styrene butadiene rubber (SBR) blends in order to access in-depth knowledge of polymers along the molecular weight distribution (MWD). In the BR-SBR case, individual polymers differ in chemical composition but share almost the same MWD. Principal component analysis (PCA) gives a general overview of the data structure and attests to the feasibility of modeling blends as a binary system. MCR-ALS is then performed. It allows resolving the chromatographic coelution and validates the chosen methodology. For SBR-SBR blends, the problem is more challenging since the individual elastomers present the same chemical composition. Rank deficiency is detected from the PCA data structure analysis. MCR-ALS is thus performed on column-wise augmented matrices. It brings very useful insight into the composition of the analyzed blends. In particular, a weak change in the composition of individual SBR in the MWD's lowest mass region is revealed.

[Haemorrhagic cellulitis: three cases]. / Erysipèle hémorragique: intérêt d'une courte corticothérapie adjuvante (3 cas).

BACKGROUND: Haemorrhagic erysipelas (cellulitis) is a recently described clinical condition. We report 3 new cases of this rare bacterial dermatosis requiring both antibiotics and systemic corticosteroids for complete resolution. CASE REPORTS: Case 1 was a 75 year-old male patient, with a past history of hypertension and diabetes mellitus. Case 2 was a 69 year-old female patient with a past history of hepatic cirrhosis. Case 3 was a 56 year-old female patient without medical past history, except for obesity. All patients presented with a haemorrhagic and bullous erysipelas of the leg without clinical improvement under parenteral antibiotics. In all cases, adjuvant systemic corticosteroids (prednisone: 0.5 mg/kg/d) for 5-8 days in addition to antibiotics provided dramatic and complete resolution of skin lesions and disappearance of pain and fever. DISCUSSION: Haemorrhagic cellulitis may be misdiagnosed as necrotizing fasciitis because of ecchymotic areas with frequent bullae resulting in haemorrhagic crusts and partial inefficacy of antibiotics given alone. Adjuvant anticoagulant therapy or coagulation abnormalities may have facilitated the clinical condition in 2 of our 3 cases. The efficacy of adjuvant systemic corticosteroids during 5-8 days, in addition to antibiotics is the hallmark of this syndrome.