Publications by authors named "Michael Robb"

We present a strategy for the modeling of charge carrier dynamics in organic semiconductors using conventional quantum chemistry methods, including the analytic gradient for nuclear motion. The theoretical approach uses real-time CASSCF (Ehrenfest) all-electron dynamics coupled to classical nuclear dynamics for the special case of a small number (4-8) of molecular units. The objective is to obtain mechanistic/atomistic insight at the electronic structure level, relating to spin density dynamics, to the effect of crystal structure (e.

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Background: Infants and toddlers engage with digital media about 1-3 hours per day with a growing proportion of time spent on YouTube.

Aim: Examined content of YouTube videos viewed by children 0-35.9 months of age and predictors of YouTube content characteristics.

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Introduction: The Speech Efficiency Score (SES) serves as an acoustic metric for assessing fluency in conversational speech within the temporal domain. This study leverages SES to investigate conversational speech efficiency among native speakers of American English (AE) compared to speakers of Mandarin-accented English (MAE).

Methods: SES, speaking rate, articulation rate, and vocabulary diversity were measured and compared between two groups: native AE speakers and MAE speakers.

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We report a protocol for the implementation of "reaction path following" from a transition state through a conical intersection, including both the path curvature induced by the derivative coupling and the corresponding induced electronic coherences. This protocol focuses on the "central" Gaussian wavepacket (initially unexcited) in the quantum Ehrenfest (QuEh) method. Like the reaction path following, the normal mode corresponding to the imaginary frequency at the transition state is given an initial momentum.

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Background: The true burden of Lyme disease in primary care in Scotland is unknown. Epidemiological data are currently based on laboratory-confirmed reports as there is no mandatory reporting of clinical cases.

Aim: To analyse data from general practice in NHS Highland (North) over a 6-year period to assess the incidence and management of Lyme disease in primary care.

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Background And Aim: To examine whether the noise components in distress cries of term infants differed from very preterm infants whose cries were collected at a comparable "corrected" gestational age.

Methods: Distress cries were collected from 20 term and 20 preterm infants. The cries were acoustically examined for the occurrence of aperiodic phonatory behavior within and across moments of crying.

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We present a theoretical study of intersystem crossing (ISC) in acrolein and ketene with the Ehrenfest method that can describe a superposition of singlet and triplet states. Our simulations illustrate a new mechanistic effect of ISC, namely, that a superposition of singlets and triplets yields nonadiabatic dynamics characteristic of that superposition rather than the constituent state potential energy surfaces. This effect is particularly significant in ketene, where mixing of singlet and triplet states along the approach to a singlet/singlet conical intersection occurs, with the spin-orbit coupling (SOC) remaining small throughout.

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In this work, we have studied the nuclear and electron dynamics in the glycine cation starting from localized hole states using the quantum Ehrenfest method. The nuclear dynamics is controlled both by the initial gradient and by the instantaneous gradient that results from the oscillatory electron dynamics (charge migration). We have used the Fourier transform (FT) of the spin densities to identify the "normal modes" of the electron dynamics.

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Background: Atypical cries have been identified in infants with neurological dysfunction. The aim of this study was to conduct a systematic review and meta-analysis to appraise existing evidence for associations between acoustic cry characteristics and neurological dysfunction in infants aged 18 months or less.

Methods: PubMed/MEDLINE, PsycINFO, CINAHL, and Embase were searched for original, peer-reviewed studies published in English reporting cry variables in infants aged 18 months or less with or at risk of neurological dysfunction.

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Introduction: This study examined the relative timing in individuals with dysarthria secondary to amyotrophic lateral sclerosis (ALS). The aim was to examine whether the relative timing was influenced by severity of dysarthria and phonetic complexity of the speech being produced.

Methods: Twenty-one adults with dysarthria secondary to ALS, who presented with a range of dysarthria severity, participated in the study.

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The primary event occurring during the E-to-Z photoisomerization reaction of retinal protonated Schiff base (rPSB) is single-to-double bond inversion. In this work we examine the nuclear dynamics that occurs when the initial excited state is a superposition of the S and S electronic excited states that might be created in a laser experiment. The nuclear dynamics is dominated by double bond inversion that is parallel to the derivative coupling vector of S and S.

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The current study aimed to explore the frequency and types of stuttering in the oral reading and conversational samples of Arabic adults who stutter (AWS). Twelve Kuwaiti-Arabic AWS (mean age: 27.3 years) participated in the study.

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This cross-sectional study quantifies the number and duration of distinct advertisements that appear during child-directed videos on a video-sharing platform as well as the frequency of age-inappropriate ads.

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The study of coupled electron-nuclear dynamics driven by coherent superpositions of electronic states is now possible in attosecond science experiments. The objective is to understand the electronic control of chemical reactivity. In this work we report coherent 8-state non-adiabatic electron-nuclear dynamics simulations of the benzene radical cation.

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In early infancy, melody provides the most salient prosodic element for language acquisition and there is huge evidence for infants' precocious aptitudes for musical and speech melody perception. Yet, a lack of knowledge remains with respect to melody patterns of infants' vocalisations. In a search for developmental regularities of cry and non-cry vocalisations and for building blocks of prosody (intonation) over the first 6 months of life, more than 67,500 melodies (fundamental frequency contours) of 277 healthy infants from monolingual German families were quantitatively analysed.

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The SARS-CoV-2 virus spreading across the world has led to surges of COVID-19 illness, hospitalizations, and death. The complex and multifaceted pathophysiology of life-threatening COVID-19 illness including viral mediated organ damage, cytokine storm, and thrombosis warrants early interventions to address all components of the devastating illness. In countries where therapeutic nihilism is prevalent, patients endure escalating symptoms and without early treatment can succumb to delayed in-hospital care and death.

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Experts have expressed concerns about the lack of evidence demonstrating that children's "educational" applications (apps) have educational value. This study aimed to operationalize Hirsh-Pasek, Zosh, et al.'s (2015) Four Pillars of Learning into a reliable coding scheme (Pillar 1: Active Learning, Pillar 2: Engagement in the Learning Process, Pillar 3: Meaningful Learning, Pillar 4: Social Interaction), describe the educational quality of commercially-available apps, and examine differences in educational quality between free and paid apps.

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This study examined the oral reading and conversational speech of eight bilinguals who stutter (BWS). The participants spoke Omani Arabic as the dominant and English as the less-dominant language. The samples were examined with particular reference to the production of overall disfluency, stuttering-like disfluencies (SLDs) and other-disfluencies (ODs) occurring at the syllable and word level.

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We describe the implementation of a laser control pulse in the quantum-Ehrenfest method, a molecular quantum dynamics method that solves the time-dependent Schrödinger equation for both electrons and nuclei. The oscillating electric field-dipole interaction is incorporated directly in the one-electron Hamiltonian of the electronic structure part of the algorithm. We then use the coupled electron-nuclear dynamics of the π-system in the allene radical cation (•CH=C=CH) as a simple model of a pump-control experiment.

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Purpose Instances of laryngeal constriction have been noted as a feature of infant vocal development. The purpose of this study was to directly evaluate the developmental occurrence of laryngeal constriction phenomena in infant crying, cooing, and babbling vocalizations. Method The cry and noncry vocalizations of 20 healthy term-born infants between the ages of 1 and 7 months were examined for instances of laryngeal constriction.

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Recent studies indicate functional cerebral hemispheric processing differences between monolinguals and bilinguals who stutter, as well as monolinguals and bilinguals who do not stutter. Eighty native German speakers, half of whom were also proficient speakers of English as a second language (L2), were assessed on a dichotic listening paradigm using CV syllables as stimuli. The participants were organised into four different groups according to speech status and language ability: 20 monolinguals who stutter, 20 bilinguals who stutter, 20 monolinguals who do not stutter, and 20 bilinguals who do not stutter.

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RASSCF calculations of vertical excitation energies were carried out on a benchmark set of 19 organic molecules studied by Thiel and co-workers [ J. Chem. Phys.

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Quantum dynamics simulations are an important tool to evaluate molecular behaviour including the, often key, quantum nature of the system. In this paper we present an algorithm that is able to simulate the time evolution of a molecule after photo-excitation into a manifold of states. The direct dynamics variational multi-configurational Gaussian (DD-vMCG) method circumvents the computational bottleneck problems of traditional grid-based methods by computing the potential energy functions on-the-fly, i.

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An algorithm is described for quantum dynamics where an Ehrenfest potential is combined with fully quantum nuclear motion (Quantum-Ehrenfest, Qu-Eh). The method is related to the single-set variational multi-configuration Gaussian approach (vMCG) but has the advantage that only a single quantum chemistry computation is required at each time step since there is only a single time-dependent potential surface. Also shown is the close relationship to the "exact factorization method.

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Purpose: Infant vocal durations have been studied from a variety of perspectives, including medical, social, and linguistic. The resultant developmental profile across the first 6 months of life, however, is still far from clear. The purpose of this study was to evaluate the durational properties of infant vocalizations from the unique perspective of voice quality.

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