Untangle the structural and random zeros in statistical modelings

Count data with structural zeros are common in public health applications. There are considerable researches focusing on zero-inflated models such as zero-inflated Poisson (ZIP) and zero-inflated Negative Binomial (ZINB) models for such zero-inflated count data when used as response variable. However, when such variables are used as predictors, the difference between structural and random zeros is often ignored and may result in biased estimates. One remedy is to include an indicator of the structural zero in the model as a predictor if observed. However, structural zeros are often not observed in practice, in which case no statistical method is available to address the bias issue. This paper is aimed to fill this methodological gap by developing parametric methods to model zero-inflated count data when used as predictors based on the maximum likelihood approach. The response variable can be any type of data including continuous, binary, count or even zero-inflated count responses. Simulation studies are performed to assess the numerical performance of this new approach when sample size is small to moderate. A real data example is also used to demonstrate the application of this method

A Nanophotonic Structure Containing Living Photosynthetic Bacteria

Photosynthetic organisms rely on a series of self-assembled nanostructures with tuned electronic energy levels in order to transport energy from where it is collected by photon absorption, to reaction centers where the energy is used to drive chemical reactions. In the photosynthetic bacteria Chlorobaculum tepidum, a member of the green sulfur bacteria family, light is absorbed by large antenna complexes called chlorosomes to create an exciton. The exciton is transferred to a protein baseplate attached to the chlorosome, before migrating through the Fenna-Matthews-Olson complex to the reaction center. Here, it is shown that by placing living Chlorobaculum tepidum bacteria within a photonic microcavity, the strong exciton-photon coupling regime between a confined cavity mode and exciton states of the chlorosome can be accessed, whereby a coherent exchange of energy between the bacteria and cavity mode results in the formation of polariton states. The polaritons have energy distinct from that of the exciton which can be tuned by modifying the energy of the optical modes of the microcavity. It is believed that this is the first demonstration of the modification of energy levels within living biological systems using a photonic structure

Sufficient Covariate, Propensity Variable and Doubly Robust Estimation

Statistical causal inference from observational studies often requires adjustment for a possibly multi-dimensional variable, where dimension reduction is crucial. The propensity score, first introduced by Rosenbaum and Rubin, is a popular approach to such reduction. We address causal inference within Dawid's decision-theoretic framework, where it is essential to pay attention to sufficient covariates and their properties. We examine the role of a propensity variable in a normal linear model. We investigate both population-based and sample-based linear regressions, with adjustments for a multivariate covariate and for a propensity variable. In addition, we study the augmented inverse probability weighted estimator, involving a combination of a response model and a propensity model. In a linear regression with homoscedasticity, a propensity variable is proved to provide the same estimated causal effect as multivariate adjustment. An estimated propensity variable may, but need not, yield better precision than the true propensity variable. The augmented inverse probability weighted estimator is doubly robust and can improve precision if the propensity model is correctly specified

Oral health promotion and programming provided by Aboriginal Community Controlled Health Organisations in South Australia

First published: 17 July 2022BACKGROUND: Aboriginal Community Controlled Health Organisations (ACCHOs) play a critical role in supporting Aboriginal and Torres Strait Islander health in Australia. This paper aims to identify and describe oral health programming and promotion provided by ACCHOs in South Australia. METHODS: All ACCHOs in South Australia were identified through the Aboriginal Health Council of South Australia. A targeted search strategy was designed to include the websites and social media pages (Facebook, Twitter, Instagram) for each organisation. Program characteristics were extracted and summarised, and oral health promotion content was analysed utilising content analysis. RESULTS: Twelve programs were identified across the 12 ACCHOs in South Australia. Of these, seven focused on oral health and five focused on nutrition. Oral health and nutrition information shared online by ACCHOs was extracted and aggregated into oral health and nutrition categories, which included reminders about visiting services, advocacy statements, oral hygiene messaging, appointment availability, education resources, and upcoming community-based activities. CONCLUSIONS: The evidence explored highlights the integral role ACCHOs play in oral health promotion and service delivery. It is critically important that ACCHOs are involved in development and implementation of oral health services to ensure programming reflects community knowledge and is effective in improving oral health equity.Brianna Poirier, Samantha Tang, Dandara Gabriela Haag, Sneha Sethi, Joanne Hedges, Lisa Jamieso

13.9% efficiency ternary nonfullerene organic solar cells featuring low-structural order

The insufficient phase separation between polymer donors and nonfullerene acceptors (NFAs) featuring low structural order disrupts efficient charge transport and increases charge recombination, consequently limiting the maximum achievable power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, an NFA IT-M has been added as the third component into the PBDB-T:m-INPOIC OSCs and is shown to effectively tune the phase separation between donor and acceptor molecules, although all components in the ternary system exhibit low degrees of structural order. The incorporation of 10 wt % IT-M into a PBDB-T:m-INPOIC binary host blend appreciably increases the length scale of phase separation, creating continuous pathways that increase and balance charge transport. This leads to an enhanced photovoltaic performance from 12.8% in the binary cell to 13.9% for the ternary cell with simultaneously improved open-circuit voltage, short-circuit current, and fill factor. This work highlights the beneficial role of ternary components in controlling the morphology of the active layer for high-performance OSCs

Regulating the morphology of fluorinated non-fullerene acceptor and polymer donor via binary solvent mixture for high efficiency polymer solar cells

Fluorinated non-fullerene acceptors (NFAs) usually have planar backbone and a higher tendency to crystallize compared to their non-fluorinated counterparts, which leads to enhanced charge mobility in organic solar cells (OSCs). However, this self-organization behavior may result in excessive phase separation with electron donors and thereby deteriorate device efficiency. Herein, we demonstrate an effective approach to tune the molecular organization of a fluorinated NFA (INPIC-4F), and its phase separation with the donor PBDB-T, by varying the casting solvent. A prolonged film drying time encourages the crystallization of INPIC-4F into spherulites and consequently results in excessive phase separation, leading to a low device power conversion efficiency (PCE) of 8.1%. Contrarily, a drying time leads to fine mixed domains with inefficient charge transport properties, resulting in a moderate device PCE of 11.4%. An intermediate film drying time results in the formation of face-on π-π stacked PBDB-T and INPIC-4F domains with continuous phase-separated networks, which facilitates light absorption, exciton dissociation as well as balanced charge transport towards the electrode, and achieves a remarkable PCE of 13.1%. This work provides a rational guide for optimizing the molecular ordering of NFAs and electron donors for high device efficiency

A Self Assembled Nanoelectronic Quantum Computer Based on the Rashba Effect in Quantum Dots

Quantum computers promise vastly enhanced computational power and an uncanny ability to solve classically intractable problems. However, few proposals exist for robust, solid state implementation of such computers where the quantum gates are sufficiently miniaturized to have nanometer-scale dimensions. Here I present a new approach whereby a complete computer with nanoscale gates might be self-assembled using chemical synthesis. Specifically, I demonstrate how to self-assemble the fundamental unit of this quantum computer - a 2-qubit universal quantum controlled-NOT gate - based on two exchange coupled multilayered quantum dots. Then I show how these gates can be wired using thiolated conjugated molecules as electrical connectors. A qubit is encoded in the ground state of a quantum dot spin-split by the Rashba interaction. Arbitrary qubit rotations are effected by bringing the spin splitting energy in a target quantum dot in resonance with a global ac magnetic field by applying a potential pulse of appropriate amplitude and duration to the dot. The controlled dynamics of the 2-qubit controlled-NOT operation (XOR) can be realized by exploiting the exchange coupling with the nearest neighboring dot. A complete prescription for initialization of the computer and data input/output operations is presented.Comment: 22 pages, 4 figure

Volume element structure and roton-maxon-phonon excitations in superfluid helium beyond the Gross-Pitaevskii approximation

We propose a theory which deals with the structure and interactions of volume elements in liquid helium II. The approach consists of two nested models linked via parametric space. The short-wavelength part describes the interior structure of the fluid element using a non-perturbative approach based on the logarithmic wave equation; it suggests the Gaussian-like behaviour of the element's interior density and interparticle interaction potential. The long-wavelength part is the quantum many-body theory of such elements which deals with their dynamics and interactions. Our approach leads to a unified description of the phonon, maxon and roton excitations, and has noteworthy agreement with experiment: with one essential parameter to fit we reproduce at high accuracy not only the roton minimum but also the neighboring local maximum as well as the sound velocity and structure factor.Comment: 9 pages, 6 figure

Tensor Correlations Measured in 3He(e,e'pp)n

We have measured the 3He(e,e'pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum, $p_{tot}$. For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low $p_{tot}$ and rises to approximately 0.5 at large $p_{tot}$. This shows the dominance of tensor over central correlations at this relative momentum.Comment: 4 pages, 4 figures, submitted to PR

Measurement of the nuclear multiplicity ratio for Ks0K^0_s hadronization at CLAS

The influence of cold nuclear matter on lepto-production of hadrons in semi-inclusive deep inelastic scattering is measured using the CLAS detector in Hall B at Jefferson Lab and a 5.014 GeV electron beam. We report the $K_s^0$ multiplicity ratios for targets of C, Fe, and Pb relative to deuterium as a function of the fractional virtual photon energy $z$ transferred to the $K_s^0$ and the transverse momentum squared $p_{T}^2$ of the $K_s^0$. We find that the multiplicity ratios for $K^0_s$ are reduced in the nuclear medium at high $z$ and low $p_{T}^2$, with a trend for the $K^0_s$ transverse momentum to be broadened in the nucleus for large $p_{T}^2$.Comment: Submitted to Phys. Lett.