Finite momentum condensation in a pumped microcavity

We calculate the absorption spectra of a semiconductor microcavity into which a non-equilibrium exciton population has been pumped. We predict strong peaks in the spectrum corresponding to collective modes analogous to the Cooper modes in superconductors and fermionic atomic gases. These modes can become unstable, leading to the formation of off-equilibrium quantum condensates. We calculate a phase diagram for condensation, and show that the dominant instabilities can be at a finite momentum. Thus we predict the formation of inhomogeneous condensates, similar to Fulde-Ferrel-Larkin-Ovchinnikov states.Comment: 7 pages, 4 figures, updated to accepted versio

Measuring patients' views: a bifactor model of distinct patient-reported outcomes in psychosis

Background Patient-reported outcomes (PROs) are widely used for evaluating the care of patients with psychosis. Previous studies have reported a considerable overlap in the information captured by measures designed to assess different outcomes. This may impair the validity of PROs and makes an a priori choice of the most appropriate measure difficult when assessing treatment benefits for patients. We aimed to investigate the extent to which four widely established PROs [subjective quality of life (SQOL), needs for care, treatment satisfaction and the therapeutic relationship] provide distinct information independent from this overlap. Method Analyses, based on item response modelling, were conducted on measures of SQOL, needs for care, treatment satisfaction and the therapeutic relationship in two large samples of patients with psychosis. Results In both samples, a bifactor model matched the data best, suggesting sufficiently strong concept factors to allow for four distinct PRO scales. These were independent from overlap across measures due to a general appraisal tendency of patients for positive or negative ratings and shared domain content. The overlap partially impaired the ability of items to discriminate precisely between patients from lower and higher PRO levels. We found that widely used sum scores were strongly affected by the general appraisal tendency. Conclusions Four widely established PROs can provide distinct information independent from overlap across measures. The findings may inform the use and further development of PROs in the evaluation of treatments for psychosis

The impact of intellectual disability and sport expertise on cognitive and executive functions.

Our aim was to identify the suitability of three assessment tools (i.e., Flanker test, Updating Word Span, and Color Trails Test) for future inclusion in the classification process of elite Paralympic athletes with intellectual disability and to assess the strength of the relation between Executive function (EF) and intelligence. Cognitive and EF assessments were performed on 59 participants, divided into four groups according to their cognitive level (with versus without intellectual disability) and sport expertise (athlete versus novice). Inhibition and working memory update skills were implicated in people with intellectual disability. For set-shifting, a more nuanced picture was observed. Strong associations between EF and intelligence was found in people with intellectual disability. Working memory updating and set-shifting are relevant EF skills to assess in the context of elite sport; however, culture-free alternatives for the Updating Word Span test are needed, and alternatives to the Color Trails Test, less reliant on literacy skills are required

Extended BEG Model of Monhalogenated Methanes Physisorbed on Ionic Crystals

The 2D dielectric phases and phase transitions of adsorbed dipolar molecules are modeled using a dilute spin-one Ising model. This model is studied in the Blume–Emery–Griffiths formalism, using a mean-field approximation, where the interaction parameters are uniquely determined from the system interaction energies using an averaging procedure. The model is applied to four monhalogenated methane species physisorbed on MgO(1 0 0) and NaCl(1 0 0) surfaces using previous experimental and theoretical studies to estimate the interaction energy parameters. We find that temperature- and coverage-dependent antiferroelectric to ferroelectric, coverage-dependent ferroelectric up to ferroelectric down, reentrant ferroelectric to ferrielectric, and order-disorder dipole phase transitions can occur. Phase diagrams based on this model are presented

Enhancing the Sensitivity of SMS Fiber Sensors by the Use of High Refractive Index Coatings

This paper presents a study on the behavior of single-mode/multimode/single-mode sensors with diamond-like carbon coating of high refractive index. Spectra and response for different values of the external medium refractive index are recorded and analyzed

Synchrotron X-ray Diffraction of Layering Transitions of Multilayer Nitrogen Physisorbed on Graphite

We use synchrotron x-ray diffraction for structural analysis of the behavior of multilayer nitrogen films physisorbed on graphite foam. We provide structural information and concentrations of 2D and 3D solid phases at a coverage of Θ = 8 ML (Θ / 1 ML for a %3 x %3 structure) for temperatures from below the bulk α-ß transition temperature [Tα-ß = 34 0.5 K] to above the bulk triple point [Ttp = 63 K]. Our data indicate layering begins near Tα-ß, with subsequent layering occurring as the temperature is raised; all bulk nitrogen forms disordered film layers by 48 K at Θ = 8 ML. Our results are consistent with ellipsometry studies of nitrogen on HOPG which found multilayer nitrogen on single crystal graphite to undergo a series of layering transitions above the bulk nitrogen α-ß structural transition.[U.G. Volkmann, and K. Knorr, Phys. Rev. Lett. 1991, 66, 473.] The effect of adsorption on a graphite foam substrate, which results in capillary condensation and finite size effects, is limited to a broadening and overlap of the discrete transition temperatures observed on a single crystal substrate. A phase diagram for coverages above 2 ML is proposed, summarizing this and previous work

A Compact EMAT Receiver for Ultrasonic Testing at Elevated Temperatures

For the past several years, the AISI and several national laboratories have cooperated on a program to develop ultrasonic transducers that can be used in steel mills at the highest temperatures encountered during the processing of the solid metal {1}. To date, pulsed laser light focused on the surface appears to make a satisfactory generator or transmitter for ultrasonic pulses while the EMAT or Electromagnetic Acoustic Transducer appears to hold the greatest promise for the receiver {2}. Both of these essentially noncontact devices can be made to withstand the very hot environmnent and they are not very sensitive to the quality of the surface