A report on the USL NASA/RECON project. Part 1: The development of a transportable, university level, IS and R educational program

A project is described which has as its goal the production of a set of system-independent, discipline-independent, transportable college level courses to educate science and engineering students in the use of large-scale information storage and retrieval systems. This project is being conducted with the cooperation and sponsorship of NASA by R and D teams at the University of Southwest Louisiana and Southern University. Chapter 1 is an introduction, providing an overview and a listing of the management phases. Chapter 2 furnishes general information regarding accomplishments in areas under development. Chapter 3 deals with the development of the course materials by presenting a series of diagrams and keys to depict the progress and interrelationships of various tasks and sub-tasks. Chapter 4 presents plans for activities to be conducted to complete and deliver course materials. The final chapter is a summary of project objectives, methods, plans, and accomplishments

Accurate near-field calculation in the rigorous coupled-wave analysis method

The rigorous coupled-wave analysis (RCWA) is one of the most successful and widely used methods for modeling periodic optical structures. It yields fast convergence of the electromagnetic far-field and has been adapted to model various optical devices and wave configurations. In this article, we investigate the accuracy with which the electromagnetic near-field can be calculated by using RCWA and explain the observed slow convergence and numerical artifacts from which it suffers, namely unphysical oscillations at material boundaries due to the Gibb's phenomenon. In order to alleviate these shortcomings, we also introduce a mathematical formulation for accurate near-field calculation in RCWA, for one- and two-dimensional straight and slanted diffraction gratings. This accurate near-field computational approach is tested and evaluated for several representative test-structures and configurations in order to illustrate the advantages provided by the proposed modified formulation of the RCWA.Comment: 13 pages, 12 figure

The experience of adults with multimorbidity: a qualitative study

Background: Findings from several countries indicate that the prevalence of multimorbidity is very high among clients of primary healthcare. A deeper understanding of patients’ experiences from their own perspective can greatly enrich any intervention to help them live as well as possible with multimorbidity. Objective: To describe the fundamental structure of adults’ experience with multimorbidity. Design: A phenomenological study was undertaken to describe the experiences of 11 adults with multimorbidity. These adults participated in two semi-structured interviews, the content of which was rigorously analyzed. Results: At the core of the study participants’ multimorbidity experience are the impression of aging prematurely, difficulties with self-care management, and issues with access to the healthcare system, which contribute to the problem’s complexity. Despite these issues, participants with multimorbidity report attempting to take control of their situation and adjusting to daily living. Conclusions: The description of this experience, through the systemic vision of participants, provides a better understanding of the realities experienced by people with multimorbidity.Journal of Comorbidity 2014;4(1):11–2

Nonlinear generalized source method for modeling second-harmonic generation in diffraction gratings

We introduce a versatile numerical method for modeling light diffraction in periodically patterned photonic structures containing quadratically nonlinear non-centrosymmetric optical materials. Our approach extends the generalized source method to nonlinear optical interactions by incorporating the contribution of nonlinear polarization sources to the diffracted field in the algorithm. We derive the mathematical formalism underlying the numerical method and introduce the Fourier-factorization suitable for nonlinear calculations. The numerical efficiency and runtime characteristics of the method are investigated in a set of benchmark calculations: the results corresponding to the fundamental frequency are compared to those obtained from a reference method and the beneficial effects of the modified Fourier-factorization rule on the accuracy of the nonlinear computations is demonstrated. In order to illustrate the capabilities of our method, we employ it to demonstrate strong enhancement of second-harmonic generated in one- and two-dimensional optical gratings resonantly coupled to a slab waveguide. Our method can be easily extended to other types of nonlinear optical interactions by simply incorporating the corresponding nonlinear polarization sources in the algorithm.Comment: 12 pages, 8 figure

Benchmarking Deep Learning Architectures for Predicting Readmission to the ICU and Describing Patients-at-Risk

Objective: To compare different deep learning architectures for predicting the risk of readmission within 30 days of discharge from the intensive care unit (ICU). The interpretability of attention-based models is leveraged to describe patients-at-risk. Methods: Several deep learning architectures making use of attention mechanisms, recurrent layers, neural ordinary differential equations (ODEs), and medical concept embeddings with time-aware attention were trained using publicly available electronic medical record data (MIMIC-III) associated with 45,298 ICU stays for 33,150 patients. Bayesian inference was used to compute the posterior over weights of an attention-based model. Odds ratios associated with an increased risk of readmission were computed for static variables. Diagnoses, procedures, medications, and vital signs were ranked according to the associated risk of readmission. Results: A recurrent neural network, with time dynamics of code embeddings computed by neural ODEs, achieved the highest average precision of 0.331 (AUROC: 0.739, F1-Score: 0.372). Predictive accuracy was comparable across neural network architectures. Groups of patients at risk included those suffering from infectious complications, with chronic or progressive conditions, and for whom standard medical care was not suitable. Conclusions: Attention-based networks may be preferable to recurrent networks if an interpretable model is required, at only marginal cost in predictive accuracy

Determination of the Rb ng-series quantum defect by electric-field-induced resonant energy transfer between cold Rydberg atoms

Resonant energy transfer between cold Rydberg atoms was used to determine Rydberg atom energy levels, at precisions approaching those obtainable in microwave spectroscopy. Laser cooled Rb atoms from a magneto-optical trap were optically excited to 32d Rydberg states. The two-atom process 32d(j=5/2) + 32d(j=5/2) -> 34p(j=3/2) + 30g is resonant at an electric field of approximately 0.3 V/cm. This process is driven by the electric dipole-dipole interaction, which is allowed due to the partial f character that the g state acquires in an electric field. The experimentally observed resonant field, together with the Stark map calculation is used to make a determination of the Rb ng-series quantum defect: delta_g (n=30) = 0.00405(6)

Constraining Stellar Feedback: Shock-ionized Gas in Nearby Starburst Galaxies

(abridged) We investigate the properties of feedback-driven shocks in 8 nearby starburst galaxies using narrow-band imaging data from the Hubble Space Telescope (HST). We identify the shock--ionized component via the line diagnostic diagram \oiii/\hb vs. \sii (or \nii)/\ha, applied to resolved regions 3--15 pc in size. We divide our sample into three sub-samples: sub-solar (Holmberg II, NGC 1569, NGC 4214, NGC 4449, and NGC 5253), solar (He 2-10, NGC 3077) and super-solar (NGC 5236) for consistent shock measurements. For the sub-solar sub-sample, we derive three scaling relations: (1) $L_{shock} \propto {SFR}^{~0.62}$, (2) $L_{shock} \propto {\Sigma_{SFR,HL}}^{~0.92}$, and (3) $L_{shock}/L_{tot} \propto {(L_H/L_{\odot,H})}^{-0.65}$, where $L_{shock}$ is the \ha luminosity from shock--ionized gas, ${\Sigma_{SFR,HL}}$ the SFR per unit half-light area, $L_{tot}$ the total \ha luminosity, and $L_H/L_{\odot,H}$ the absolute H-band luminosity from 2MASS normalized to solar luminosity. The other two sub--samples do not have enough number statistics, but appear to follow the first scaling relation. The energy recovered indicates that the shocks from stellar feedback in our sample galaxies are fully radiative. If the scaling relations are applicable in general to stellar feedback, our results are similar to those by Hopkins et al. (2012) for galactic super winds. This similarity should, however, be taken with caution at this point, as the underlying physics that enables the transition from radiative shocks to gas outflows in galaxies is still poorly understood.Comment: 29 pages, 14 figures, accepted for publication in the Ap

Reexamining Black-Body Shifts for Hydrogenlike Ions

We investigate black-body induced energy shifts for low-lying levels of atomic systems, with a special emphasis on transitions used in current and planned high-precision experiments on atomic hydrogen and ionized helium. Fine-structure and Lamb-shift induced black-body shifts are found to increase with the square of the nuclear charge number, whereas black-body shifts due to virtual transitions decrease with increasing nuclear charge as the fourth power of the nuclear charge. We also investigate the decay width acquired by the ground state of atomic hydrogen, due to interaction with black-body photons. The corresponding width is due to an instability against excitation to higher excited atomic levels, and due to black-body induced ionization. These effects limit the lifetime of even the most fundamental, a priori absolutely stable, "asymptotic" state of atomic theory, namely the ground state of atomic hydrogen.Comment: 11 pages; LaTe

Intercomparison of Multiple UV-LIF Spectrometers using the Aerosol Challenge Simulator

Measurements of primary biological aerosol particles (PBAPs) have been conducted worldwide using ultraviolet light-induced fluorescence (UV-LIF) spectrometers. However, how these instruments detect and respond to known biological and non-biological particles, and how they compare, remains uncertain due to limited laboratory intercomparisons. Using the Defence Science and Technology Laboratory, Aerosol Challenge Simulator (ACS), controlled concentrations of biological and non-biological aerosol particles, singly or as mixtures, were produced for testing and intercomparison of multiple versions of the Wideband Integrated Bioaerosol Spectrometer (WIBS) and Multiparameter Bioaerosol Spectrometer (MBS). Although the results suggest some challenges in discriminating biological particle types across different versions of the same UV-LIF instrument, a difference in fluorescence intensity between the non-biological and biological samples could be identified for most instruments. While lower concentrations of fluorescent particles were detected by the MBS, the MBS demonstrates the potential to discriminate between pollen and other biological particles. This study presents the first published technical summary and use of the ACS for instrument intercomparisons. Within this work a clear overview of the data pre-processing is also presented, and documentation of instrument version/model numbers is suggested to assess potential instrument variations between different versions of the same instrument. Further laboratory studies sampling different particle types are suggested before use in quantifying impact on ambient classification.Peer reviewe