7,306 research outputs found
Exciton-polariton emission from organic semiconductor optical waveguides
We photo-excite slab polymer waveguides doped with J-aggregating dye
molecules and measure the leaky emission from strongly coupled waveguide
exciton polariton modes at room temperature. We show that the momentum of the
waveguide exciton polaritons can be controlled by modifying the thickness of
the excitonic waveguide. Non-resonantly pumped excitons in the slab excitonic
waveguide decay into transverse electric and transverse magnetic strongly
coupled exciton waveguide modes with radial symmetry. These leak to cones of
light with radial and azimuthal polarizations
Randomly poled crystals as a source of photon pairs
Generation of photon pairs from randomly poled nonlinear crystals is
investigated using analytically soluble model and numerical calculations.
Randomly poled crystals are discovered as sources of entangled ultra broad-band
signal and idler fields. Their photon-pair generation rates scale linearly with
the number of domains. Entanglement times as short as several fs can be
reached. Comparison with chirped periodically-poled structures is given and
reveals close similarity.Comment: 13 pages, 29 figure
Effect of W, LR, and LM Tests on the Performance of Preliminary Test Ridge Regression Estimators
This paper combines the idea of preliminary test and ridge regression methodology, when it is suspected that the regression coefficients may be restricted to a subspace. The preliminary test ridge regression estimators (PTRRE) based on the Wald (W), Likelihood Ratio (LR) and Lagrangian Multiplier (LM) tests are considered. The bias and the mean square errors (MSE) of the proposed estimators are derived under both null and alternative hypotheses. By studying the MSE criterion, the regions of optimality of the estimators are determined. Under the null hypothesis, the PTRRE based on LM test has the smallest risk followed by the estimators based on LR and W tests. However, the PTRRE based on W test performs the best followed by the LR and LM based estimators when the parameter moves away from the subspace of the restrictions. The conditions of superiority of the proposed estimator for both ridge parameter k and departure parameter (triangle symbol) are provided. Some graphical representations have been presented which support the findings of the paper. Some tables for maximum and minimum guaranteed relative efficiency of the proposed estimators have been provided. These tables allow us to determine the optimum level of significance corresponding to the optimum estimators among proposed estimators. Finally, we concluded that the optimum choice of the level of significance becomes the traditional choice by using the W test for all non-negative ridge parameter, k.Dominance; Lagrangian Multiplier; Likelihood Ratio Test; MSE; Non-central Chisquare and F; Ridge Regression; Superiority; Wald Test.
A Minority of Patients with Type 1 Diabetes Routinely Downloads and Retrospectively Reviews Device Data.
BackgroundIn type 1 diabetes (T1D), periodic review of blood glucose and insulin dosing should be performed, but it is not known how often patients review these data on their own. We describe the proportion of patients with T1D who routinely downloaded and reviewed their data at home.Materials and methodsA cross-sectional survey of 155 adults and 185 caregivers of children with T1D at a single academic institution was performed. "Routine Downloaders" (downloaded four or more times in the past year) were also considered "Routine Reviewers" if they reviewed their data most of the time they downloaded from devices. Logistic regression was used to identify factors associated with being a Routine Reviewer.ResultsOnly 31% of adults and 56% of caregivers reported ever downloading data from one or more devices, whereas 20% and 40%, respectively, were considered Routine Downloaders. Only 12% of adults and 27% of caregivers were Routine Reviewers. Mean hemoglobin A1c was lower in Routine Reviewers compared with non-Routine Reviewers (7.2±1.0% vs. 8.1±1.6% [P=0.03] in adults and 7.8±1.4% vs. 8.6±1.7% [P=0.001] in children). In adjusted analysis of adults, the odds ratio of being a Routine Reviewer of one or more devices for every 10-year increase in age was 1.5 (95% confidence interval, 1.1, 2.1 [P=0.02]). For every 10 years since diabetes diagnosis, the odds ratio of being a Routine Reviewer was 1.7 (95% confidence interval, 1.2, 2.4 [P=0.01]). For caregivers, there were no statistically significant factors associated with being a Routine Reviewer.ConclusionsA minority of T1D patients routinely downloads and reviews data from their devices on their own. Further research is needed to understand obstacles, provide better education and tools for self-review, and determine if patient self-review is associated with improved glycemic control
Literasi Teknologi Informasi dan Komunikasi (TIK) Masyarakat di Kawasan Mamminasata
Penelitian ini bertujuan untuk mendeskripsikan tingkat literasi Teknologi Informasi dan Komunikasi (TIK) masyarakat di kawasan Mamminasata. Penelitian ini menggunakan metode survei dengan pendekatan kuantitatif. Hasil penelitian ini menunjukkan bahwa tingkat literasi masyarakat di kawasan Mamminasata relatif masih rendah. Hanya sebagian kecil masyarakat yang literasi TIKnya relatif baik, yaitu aktivitasnya sudah sangat tergantung pada penggunaan TIK. Hasil penelitian ini juga menunjukkan bahwa pengguna TIK di kawasan Mamminasata belum merata, yaitu masih didominasi oleh kelompok usia muda dan kelompok masyarakat yang berpendidikan tinggi. Oleh karena itu, penelitian ini merekomendasikan agar dilakukan upaya-upaya peningkatan literasi TIK masyarakat secara merata, baik dari aspek usia maupun pendidikan
Role of entanglement in two-photon imaging
The use of entangled photons in an imaging system can exhibit effects that
cannot be mimicked by any other two-photon source, whatever the strength of the
correlations between the two photons. We consider a two-photon imaging system
in which one photon is used to probe a remote (transmissive or scattering)
object, while the other serves as a reference. We discuss the role of
entanglement versus correlation in such a setting, and demonstrate that
entanglement is a prerequisite for achieving distributed quantum imaging.Comment: 15 pages, 2 figure
Superpositions of the Orbital Angular Momentum for Applications in Quantum Experiments
Two different experimental techniques for preparation and analyzing
superpositions of the Gaussian and Laguerre-Gassian modes are presented. This
is done exploiting an interferometric method on the one hand and using computer
generated holograms on the other hand. It is shown that by shifting the
hologram with respect to an incoming Gaussian beam different superpositions of
the Gaussian and the Laguerre-Gaussian beam can be produced. An analytical
expression between the relative phase and the amplitudes of the modes and the
displacement of the hologram is given. The application of such orbital angular
momenta superpositions in quantum experiments such as quantum cryptography is
discussed.Comment: 18 pages, 4 figures. to appear in Journal of Optics
To make a nanomechanical Schr\"{o}dinger-cat mew
By an explicite calculation of Michelson interferometric output intensities
in the optomechanical scheme proposed by Marshall et al. (2003), an oscillatory
factor is obtained that may go down to zero just at the time a visibility
revival ought to be observed. Including a properly tuned phase shifter offers a
simple amendment to the situation. By using a Pockels phase shifter with fast
time-dependent modulation in one arm, one may obtain further possibilities to
enrich the quantum state preparation and reconstruction abilities of the
original scheme, thereby improving the chances to reliably detect genuine
quantum behaviour of a nanomechanical oscillator.Comment: For Proc. DICE-2010 (Castiglioncello), to be published in J. Phys.
Conf. Ser., 201
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