Conformational Control of Exciton-Polariton Physics in Metal - Poly(9,9-dioctylfluorene) - Metal Cavities

Control is exerted over the exciton-polariton physics in metal - Poly(9,9-dioctyl fluorene) - metal microcavities via conformational changes to the polymer backbone. Using thin-film samples containing increasing fractions of $\beta$-phase chain segments, a systematic study is reported for the mode characteristics and resulting light emission properties of cavities containing two distinct exciton sub-populations within the same semiconductor. Ultrastrong coupling for disordered glassy-phase excitons is observed from angle-resolved reflectivity measurements, with Rabi splitting energies in excess of 1.05 eV (more than 30% of the exciton transition energy) for both TE- and TM-polarized light. A splitting of the lower polariton branch is then induced via introduction of $\beta$-phase excitons and increases with their growing fraction. In all cases, the photoluminescence emanates from the lowermost polariton branch, allowing conformational control to be exerted over the emission energy and its angular variation. Dispersion-free cavities with highly saturated blue-violet emission are thus enabled. Experimental results are discussed in terms of the full Hopfield Hamiltonian generalized to the case of two exciton oscillators. The importance of taking account of the molecular characteristics of the semiconductor for an accurate description of its strong coupling behaviour is directly considered, in specific relation to the role of the vibronic structure

Health and sustainable development

If sustainable development is to mean anything, people must be healthy enough to benefit from it and not have their lives cut off prematurely. Development without health is meaningless. But the processes which are likely to occur in a world undergoing globalisation, climate change, urbanisation, population increase and many other changes, will impact upon human health in complex ways. Some of them will benefit us, others will create new or augmented threats to survival and health, while many others will have a complex mixture of effects

Magnetic fields and differential rotation on the pre-main sequence

Maps of magnetic field topologies of rapidly rotating stars obtained over the last decade or so have provided unique insight into the operation of stellar dynamos. However, for solar-type stars many of the targets imaged to date have been lower-mass zero-age main sequence stars. We present magnetic maps and differential rotation measurements of two-higher mass pre-main sequence stars HD 106506 (~10 Myrs) and HD 141943 (~15 Myrs). These stars should evolve into mid/late F-stars with predicted high differential rotation and little magnetic activity. We investigate what effect the extended convection zones of these pre-main sequence stars has on their differential rotation and magnetic topologies. ©2009 American Institute of Physic

Electricity load profile classification using Fuzzy C-Means method

This paper presents the Fuzzy C-Means (FCM) clustering method. The FCM technique assigns a degree of membership for each data set to several clusters, thus offering the opportunity to deal with load profiles that could belong to more than one group at the same time. The FCM algorithm is based on minimising a c-means objective function to determine an optimal classification. The simulation of FCM was carried out using actual sample data from Indonesia and the results are presented. Some validity index measurements was carried out to estimate the compactness of the resulting clusters or to find the optimal number of clusters for a data set

Ground-State Properties of a Rotating Bose-Einstein Condensate with Attractive Interaction

The ground state of a rotating Bose-Einstein condensate with attractive interaction in a quasi-one-dimensional torus is studied in terms of the ratio $\gamma$ of the mean-field interaction energy per particle to the single-particle energy-level spacing. The plateaus of quantized circulation are found to appear if and only if $\gamma<1$ with the lengths of the plateaus reduced due to hybridization of the condensate over different angular-momentum states.Comment: 4 pages, 2 figures, Accepted for publication in Physical Reveiw Letter

Analyzing Crop Revenue Safety Net Program Alternatives and Impacts on Producers and Program Costs

This study evaluates the policy effects of alternative program designs for federal revenue-based farm income safety net programs. Eight representative farms across Nebraska are used to stochastically simulate the financial impact of changing the current farm crop revenue-based safety net with a state revenue trigger against potential alternative programs involving guarantees at the district, county, or farm level. Results indicate that decreasing the aggregation of the revenue guarantee increases expected farm-level payments and program costs for the revenue-based safety net.agricultural policy, farm bill, farm programs, government payments, representative farms, risk management, simulation, Agricultural and Food Policy, Farm Management, Risk and Uncertainty, Q12, Q18,

Observation of a possible superflare on Proxima Centauri

We report the observation on UT 2017 July 1 of an unusually powerful flare detected in near-infrared continuum photometry of Proxima Centauri. During a campaign monitoring the star for possible exoplanet transits, we identified an increase in Sloan i' flux leading to an observed peak at BJD 2457935.996 that was at least 10 per cent over pre-flare flux in this band. It was followed by a two-component rapid decline in the first 100 s that became a slower exponential decay with time constant of 1350 s. A smaller flare event 1300 s after the first added an incremental peak flux increase of 1 per cent of pre-flare flux. Since the onset of the flare was not fully time resolved at a cadence of 62 s, its actual peak value is unknown but greater than the time average over a single exposure of 20 s. The i' band is representative of broad optical and near-IR continuum flux over which the integrated energy of the flare is 100 times the stellar luminosity. This meets the criteria that established the concept of superflares on similar stars. The resulting implied ultraviolet flux and space weather could have had an extreme effect on the atmospheres of planets within the star's otherwise habitable zone

Spin domain formation in spinor Bose-Einstein condensation

The spatial structure of the spinor Bose-Einstein condensates with the spin degrees of freedom is analyzed based on the generalized Gross-Pitaevskii equation (GP) in the light of the present spin domain experiment on m_F=\pm 1, and 0 of the hyperfine state F=1 of ^{23}Na atom gases. The GP solutions in three- and one-spatial dimensional cases reproduce the observed spin domain structures, revealing the length scale associated with the existence of the weak interaction of the spin-spin channel, other than the ordinary coherence length related to the density-density channel. The obtained domain structure in GP is compared with the result in Thomas-Fermi approximation. The former solution is found to better describe the observed features than the latter.Comment: 9 pages, 14 figure