5,689 research outputs found

    Low-Energy Shape Resonances of a Nucleobase in Water

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    When high-energy radiation passes through aqueous material, low-energy electrons are produced which cause DNA damage. Electronic states of anionic nucleobases have been suggested as an entrance channel to capture the electron. However, identifying these electronic resonances have been restricted to gas-phase electron-nucleobase studies and offer limited insight into the resonances available within the aqueous environment of DNA. Here, resonance and detachment energies of the micro-hydrated uracil pyrimidine nucleobase anion are determined by two-dimensional photoelectron spectroscopy and are shown to extrapolate linearly with cluster size. This extrapolation allows the corresponding resonance and detachment energies to be determined for uracil in aqueous solution as well as the reorganization energy associated with electron capture. Two shape resonances are clearly identified that can capture low-energy electrons and subsequently form the radical anion by solvent stabilization and internal conversion to the ground electronic state. The resonances and their dynamics probed here are the nucleobase-centered doorway states for low-energy electron capture and damage in DNA

    ROTATIONAL SPECTRA AND NUCLEAR QUADRUPOLE COUPLING CONSTANTS OF IODOIMIDAZOLES

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    The microwave spectra of two isomers of iodoimidazole have been recorded and assigned with resolution of their nuclear quadrupole coupling constants. These constants have been analysed in terms of the conjugation between the lone pairs on the iodine atom and the aromatic pipi-bonding system, and the effect of this conjugation on the distribution of pipi-electron density in the ring. A comparison of these properties has been made between iodoimidazole and other 5- and 6-membered aromatic rings bonded to halogen atoms

    ROTATIONAL SPECTRA AND NUCLEAR QUADRUPOLE COUPLING CONSTANTS OF 4-HALOPYRAZOLES C3N2H3X (X = Br, I)

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    The microwave spectra of the heteroaromatic molecules 4-bromopyrazole and 4-iodopyrazole have been recorded for the first time, along with their textit{N}-deuterated isotopologues. These species have recently been found to be useful in structural determination of proteins due to their ability to attach at a variety of binding sites.footnote{J. D. Bauman, J. J. E. K. Harrison, and E. Arnold, textit{IUCrJ} 2016, 3, 51--60} The nuclear quadrupole coupling constants have been fitted, and these have been used to determine the nature of the C-X bond, and related to the strength of the halogen bonds formed by the molecules

    Prenatal development is linked to bronchial reactivity: epidemiological and animal model evidence

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    Chronic cardiorespiratory disease is associated with low birthweight suggesting the importance of the developmental environment. Prenatal factors affecting fetal growth are believed important, but the underlying mechanisms are unknown. The influence of developmental programming on bronchial hyperreactivity is investigated in an animal model and evidence for comparable associations is sought in humans. Pregnant Wistar rats were fed either control or protein-restricted diets throughout pregnancy. Bronchoconstrictor responses were recorded from offspring bronchial segments. Morphometric analysis of paraffin-embedded lung sections was conducted. In a human mother-child cohort ultrasound measurements of fetal growth were related to bronchial hyperreactivity, measured at age six years using methacholine. Protein-restricted rats' offspring demonstrated greater bronchoconstriction than controls. Airway structure was not altered. Children with lesser abdominal circumference growth during 11-19 weeks' gestation had greater bronchial hyperreactivity than those with more rapid abdominal growth. Imbalanced maternal nutrition during pregnancy results in offspring bronchial hyperreactivity. Prenatal environmental influences might play a comparable role in humans

    Supersymmetric Homogeneous Quantum Cosmologies Coupled to a Scalar Field

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    Recent work on N=2N=2 supersymmetric Bianchi type IX cosmologies coupled to a scalar field is extended to a general treatment of homogeneous quantum cosmologies with explicitely solvable momentum constraints, i.e. Bianchi types I, II, VII, VIII besides the Bianchi type IX, and special cases, namely the Friedmann universes, the Kantowski-Sachs space, and Taub-NUT space. Besides the earlier explicit solution of the Wheeler DeWitt equation for Bianchi type IX, describing a virtual wormhole fluctuation, an additional explicit solution is given and identified with the `no-boundary state'.Comment: 23 PAGE

    Development and validation of PozQoL: A scale to assess quality of life of PLHIV

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    Background: Advances in medical treatment for HIV are driving major changes in HIV policy and practice, including the encouragement of intake and adherence to HIV antiretroviral treatment (ART) by people living with HIV (PLHIV) for both personal and public health benefits. However, there is increasing recognition that achieving these goals will require a concurrent focus on the broader psychological and social wellbeing of PLHIV. Increasingly calls are being been made to incorporate a stronger focus on quality of life (QoL) of PLHIV into HIV prevention policy. In order to achieve this goal, HIV community, support and healthcare services need a valid, short and practical way to evaluate QoL of PLHIV accessing their programs. Current QoL measures are either long, complex, restricted in their use, or expensive. To address these shortcomings, the PozQoL study aimed to develop, test and validate a short and freely available scale assessing QoL among PLHIV. Methods: Drawing on a literature review, the prioritisation of domains and development of the initial pool of items was conducted in consultation with PLHIV community organisations in Australia. The items covered health concerns, psychological, social, and functional wellbeing. Testing involved a baseline and a follow-up survey of 465 adult Australians living with HIV. Participants were recruited through social media and various community organizations nationwide. The survey included the pilot PozQoL scale and other validated measures of health and wellbeing. Results: Guided by an Exploratory Factor Analysis and conceptual considerations, a 13-item scale was developed. The PozQoL scale demonstrated high levels of fit in a Confirmatory Factor Analysis, very good internal consistency, test-retest reliability, and concurrent validity with other measures that approximated different aspects of QoL. Conclusion: The PozQoL scale has been tested in a diverse sample of adult PLHIV living in Australia, demonstrating very good reliability and validity. The insights from PLHIV and other stakeholders supported the balancing of statistical rigour and conceptual accuracy. The scale is now ready to be implemented and field-tested across a range of community, support and healthcare programs for PLHIV. This will make a significant contribution to the evaluation and enhancement of programs for PLHIV

    Dissociation energies of AgRG (RG = Ar, Kr, Xe) and AgO molecules from velocity map imaging studies

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    The near ultraviolet photodissociation dynamics of silver atom rare gas dimers have been studied by velocity map imaging. AgRG (RG = Ar, Kr, Xe) species generated by laser ablation are excited in the region of the C <- X continuum leading to direct, near threshold dissociation generating Ag* (2P3/2) + RG (1S0) products. Images recorded at excitation wavelengths throughout the C <- X continuum, coupled with known atomic energy levels, permit determination of the ground X (2SIGMA+) state dissociation energies of 85.9 +/- 23.4 cm-1 (AgAr), 149.3 +/- 22.4 cm-1 (AgKr) and 256.3 +/- 16.0 cm-1 (AgXe). Three additional photolysis processes, each yielding Ag atom photoproducts, are observed in the same spectral region. Two of these are markedly enhanced in intensity upon seeding the molecular beam with nitrous oxide, and are assigned to photodissociation of AgO at the two photon level. These features yield an improved ground state dissociation energy for AgO of 15965 +/- 81 cm-1, which is in good agreement with high level calculations. The third process results in Ag atom fragments whose kinetic energy shows anomalously weak photon energy dependence and is assigned tentatively to dissociative ionization of the silver dimer Ag2

    Anomalous post-death encounters and their positive impact on experients

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    During the bereavement process, people often report anomalous experiences that may be interpreted as evidence of the survival of the deceased’s ‘spirit’, ‘soul’, or ‘personality’. For example, Rees (1971) and Castelnovo et al. (2015) found that between 50-60% of bereaved individuals reported spontaneous anomalous experiences – most notably, ‘sensing the presence’ of the deceased. The experiences typically take the form of dreaming of the dead (Barrett, 1991-92) and sensing the presence of the deceased (Steffen & Coyle, 2011), but also include the seeing of apparitions and physical effects that are characteristic of the deceased (see Cooper, Roe, & Mitchell, 2015). Experients report that they find such experiences comforting and serve to help them come to terms with their loss (see Krippner, 2006). The present study was intended to explore these experiences in much greater depth, focusing on how they might engender ‘hope’ (Snyder, 1994), as suggested by several previous researchers (e.g., Devers, 1997; Drewry, 2003; Guggenheim & Guggenheim, 1995)
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