Light Engineering of the Polariton Landscape in Semiconductor Microcavities

We demonstrate a method to create potential barriers with polarized light beams for polaritons in semiconductor microcavities. The form of the barriers is engineered via the real space shape of a focalised beam on the sample. Their height can be determined by the visibility of the scattering waves generated in a polariton fluid interacting with them. This technique opens up the way to the creation of dynamical potentials and defects of any shape in semiconductor microcavities.Comment: 4 pages, 5 figure

Employee recognition, meaningfulness and behavioural involvement: Test of a moderated mediation model

This study examines how and under what conditions recognition practices are related to employee behavioural involvement at work. Combining social cognitive theory, social information processing theory and self-concordance theory, we develop and test a moderated mediation model in which (a) manager recognition promotes behavioural involvement both directly and indirectly through the intervening role of meaningfulness and (b) coworker recognition strengthens the benefits of manager recognition to meaningfulness and subsequent behavioural involvement. The results of a study of 130 employees provided empirical support for our model. These findings help clarify how different sources of recognition can shape the effective behavioural involvement in the workplace; they also emphasize the role of meaningfulness as an important psychological mechanism that explains the recognition–behaviour relation. The implications for theory and practice are discussed

Scavenging of aerosol particles by rain in a cloud resolving model

International audienceWe describe a below-cloud scavenging module of aerosol particles by raindrops for use in a three-dimensional mesoscale cloud resolving model. The rate of particle removal is computed by integrating the scavenging efficiency over the aerosol particle and the drop size distributions. Here the numerical integration is performed accurately with a Gauss quadrature algorithm. The efficiency of the scavenging module is partially confirmed with experimental data. More interestingly, it is illustrated by two numerical experiments: the simulation of a forced convective circulation in a tropical cloudy boundary layer and a two-dimensional simulation of an African squall line. The results show a very selective wet removal of the aerosol particles which clearly depends on the mode radius, the width and the vertical profile of concentration. Furthermore, the squall line case shows the importance of resolving internal circulations to redistribute layers of aerosol particles in order to improve estimates of particle removal by below-cloud scavenging

Comment on "Linear wave dynamics explains observations attributed to dark-solitons in a polariton quantum fluid"

In a recent preprint (arXiv:1401.1128v1) Cilibrizzi and co-workers report experiments and simulations showing the scattering of polaritons against a localised obstacle in a semiconductor microcavity. The authors observe in the linear excitation regime the formation of density and phase patterns reminiscent of those expected in the non-linear regime from the nucleation of dark solitons. Based on this observation, they conclude that previous theoretical and experimental reports on dark solitons in a polariton system should be revised. Here we comment why the results from Cilibrizzi et al. take place in a very different regime than previous investigations on dark soliton nucleation and do not reproduce all the signatures of its rich nonlinear phenomenology. First of all, Cilibrizzi et al. consider a particular type of radial excitation that strongly determines the observed patterns, while in previous reports the excitation has a plane-wave profile. Most importantly, the nonlinear relation between phase jump, soliton width and fluid velocity, and the existence of a critical velocity with the time-dependent formation of vortex-antivortex pairs are absent in the linear regime. In previous reports about dark soliton and half-dark soliton nucleation in a polariton fluid, the distinctive dark soliton physics is supported both by theory (analytical and numerical) and experiments (both continuous wave and pulsed excitation).Comment: 4 pages, 2 figure

Spatially and polarization resolved plasmon mediated transmission through continuous metal films

The experimental demonstration and characterization is made of the plasmon-mediated resonant transmission through an embedded undulated continuous thin metal film under normal incidence. 1D undulations are shown to enable a spatially resolved polarisation filtering whereas 2D undulations lead to spatially resolved, polarization independent transmission. Whereas the needed submicron microstructure lends itself in principle to CD-like low-cost mass replication by means of injection moulding and embossing, the present paper demonstrates the expected transmission effects on experimental models based on metal-coated photoresist gratings. The spectral and angular dependence in the neighbourhood of resonance are investigated and the question of the excess losses exhibited by surface plasmons is discusse

Sleep disorders and suicide attempts following discharge from residential treatment

IntroductionSuicide is a significant public health concern and its prevention remains a top clinical priority of the Veterans Health Administration. Periods of transition in care (e.g., moving from inpatient to outpatient care) represent a period of increased risk. Sleep disorders are prevalent amongst Veterans and are modifiable risk factor for suicide. The present study examined the relationship of sleep disorders to time to suicide attempt amongst Veterans known to have attempted suicide in the 180 days following discharge from a Mental Health Residential Rehabilitation Treatment Program.MethodThe present sample was comprised of all Veterans enrolled in services with the Veterans Health Administration known to have attempted suicide following discharge from a Mental Health Residential Rehabilitation Treatment Program during Fiscal Years 13 and 14 (N = 1,489). To create this sample, electronic medical record data were extracted from two VHA data sources: the Corporate Data Warehouse and the Suicide Prevention Application Network.ResultsCox regression models revealed that Veterans with a sleep disturbance (N = 1,211) had a shorter time to suicide attempt than those without a sleep disturbance [Hazard Ratio (HR) = 1.16, CI (1.02–1.32)]. A subsequent Cox regression model including age, insomnia, nightmare disorder, and alcohol dependence revealed that sleep-related breathing disorders [HR = 1.19, CI (1.01–1.38)], alcohol dependence [HR = 1.16, CI (1.02–1.33)], and age group were associated with increased risk.ConclusionFindings indicate that sleep disturbance, primarily driven by sleep-related breathing disorders, was associated with time to suicide attempt in this sample of high-risk Veterans known to have attempted suicide in the 180 days following their discharge from a Mental Health Residential Rehabilitation Treatment Program. These findings reveal an opportunity to reduce risk through the screening and treatment of sleep disorders in high-risk populations