An integration of attachment theory and reinforcement sensitivity theory

This thesis examined how relationship experiences shape people\u27s sensitivity to detect threat and reward in romantic relationships and substance use scenarios. Findings indicated that anxious individuals experienced difficulty in distinguishing between threat and reward. In contrast, avoidant individuals were quick to detect threat either fleeing or confronting the problem aggressively

Colloidal dual-band gap cell for photocatalytic hydrogen generation

We report that the internal quantum efficiency for hydrogen generation in spherical, Pt-decorated CdS nanocrystals can be tuned by quantum confinement, resulting in higher efficiencies for smaller than for larger nanocrystals (17.3% for 2.8 nm and 11.4% for 4.6 nm diameter nanocrystals). We attribute this to a larger driving force for electron and hole transfer in the smaller nanocrystals. The larger internal quantum efficiency in smaller nanocrystals enables a novel colloidal dual-band gap cell utilising differently sized nanocrystals and showing larger external quantum efficiencies than cells with only one size of nanocrystals (9.4% for 2.8 nm particles only and 14.7% for 2.8 nm and 4.6 nm nanocrystals). This represents a proof-of-principle for future colloidal tandem cell

Band gap temperature-dependence and exciton-like state in copper antimony sulphide, CuSbS2

The temperature-dependence of the band gap of the proposed photovoltaic absorber copper antimony sulphide (CuSbS2) has been studied by Fourier-transform infrared spectroscopy. The direct gap rises from 1.608 to 1.694 eV between 300 and 4.2 K. Below 200 K an exciton-like feature develops above the absorption edge at 1.82 eV. First-principles calculations evaluate band structure, band symmetries, and dipole selection rules, suggesting distinctly enhanced absorption for certain excitonic optical transitions. Striking consistency is seen between predicted dielectric and absorption spectra and those determined by ellipsometry, which reveal rapidly strengthening absorption passing 105 cm−1 at 2.2 eV. These results suggest beneficial photovoltaic performance due to strong optical absorption arising from unusually strong electron–hole interactions in polycrystalline CuSbS2 material

VEGF-A165b is an endogenous neuroprotective splice isoform of vascular endothelial growth factor A in vivo and in vitro

Vascular endothelial growth factor (VEGF) A is generated as two isoform families by alternative RNA splicing, represented by VEGF-A165a and VEGF-A165b. These isoforms have opposing actions on vascular permeability, angiogenesis, and vasodilatation. The proangiogenic VEGF-A165a isoform is neuroprotective in hippocampal, dorsal root ganglia, and retinal neurons, but its propermeability, vasodilatatory, and angiogenic properties limit its therapeutic usefulness. In contrast, a neuroprotective effect of endogenous VEGF-A165b on neurons would be advantageous for neurodegenerative pathologies. Endogenous expression of human and rat VEGF-A165b was detected in hippocampal and cortical neurons. VEGF-A165b formed a significant proportion of total VEGF-A in rat brain. Recombinant human VEGF-A165b exerted neuroprotective effects in response to multiple insults, including glutamatergic excitotoxicity in hippocampal neurons, chemotherapy-induced cytotoxicity of dorsal root ganglion neurons, and retinal ganglion cells (RGCs) in rat retinal ischemia-reperfusion injury in vivo. Neuroprotection was dependent on VEGFR2 and MEK1/2 activation but not on p38 or phosphatidylinositol 3-kinase activation. Recombinant human VEGF-A165b is a neuroprotective agent that effectively protects both peripheral and central neurons in vivo and in vitro through VEGFR2, MEK1/2, and inhibition of caspase-3 induction. VEGF-A165b may be therapeutically useful for pathologies that involve neuronal damage, including hippocampal neurodegeneration, glaucoma diabetic retinopathy, and peripheral neuropathy. The endogenous nature of VEGF-A165b expression suggests that non-isoform-specific inhibition of VEGF-A (for antiangiogenic reasons) may be damaging to retinal and sensory neurons

Estimating the COVID-19 infection fatality ratio accounting for seroreversion using statistical modelling.

Background: The infection fatality ratio (IFR) is a key statistic for estimating the burden of coronavirus disease 2019 (COVID-19) and has been continuously debated throughout the COVID-19 pandemic. The age-specific IFR can be quantified using antibody surveys to estimate total infections, but requires consideration of delay-distributions from time from infection to seroconversion, time to death, and time to seroreversion (i.e. antibody waning) alongside serologic test sensitivity and specificity. Previous IFR estimates have not fully propagated uncertainty or accounted for these potential biases, particularly seroreversion. Methods: We built a Bayesian statistical model that incorporates these factors and applied this model to simulated data and 10 serologic studies from different countries. Results: We demonstrate that seroreversion becomes a crucial factor as time accrues but is less important during first-wave, short-term dynamics. We additionally show that disaggregating surveys by regions with higher versus lower disease burden can inform serologic test specificity estimates. The overall IFR in each setting was estimated at 0.49-2.53%. Conclusion: We developed a robust statistical framework to account for full uncertainties in the parameters determining IFR. We provide code for others to apply these methods to further datasets and future epidemics

Leveraging community mortality indicators to infer COVID-19 mortality and transmission dynamics in Damascus, Syria.

The COVID-19 pandemic has resulted in substantial mortality worldwide. However, to date, countries in the Middle East and Africa have reported considerably lower mortality rates than in Europe and the Americas. Motivated by reports of an overwhelmed health system, we estimate the likely under-ascertainment of COVID-19 mortality in Damascus, Syria. Using all-cause mortality data, we fit a mathematical model of COVID-19 transmission to reported mortality, estimating that 1.25% of COVID-19 deaths (sensitivity range 1.00% - 3.00%) have been reported as of 2 September 2020. By 2 September, we estimate that 4,380 (95% CI: 3,250 - 5,550) COVID-19 deaths in Damascus may have been missed, with 39.0% (95% CI: 32.5% - 45.0%) of the population in Damascus estimated to have been infected. Accounting for under-ascertainment corroborates reports of exceeded hospital bed capacity and is validated by community-uploaded obituary notifications, which confirm extensive unreported mortality in Damascus

Database of epidemic trends and control measures during the first wave of COVID-19 in mainland China.

OBJECTIVES: In this data collation study, we aimed to provide a comprehensive database describing the epidemic trends and responses during the first wave of coronavirus disease 2019 (COVID-19) throughout the main provinces in China. METHODS: From mid-January to March 2020, we extracted publicly available data regarding the spread and control of COVID-19 from 31 provincial health authorities and major media outlets in mainland China. Based on these data, we conducted descriptive analyses of the epidemic in the six most-affected provinces. RESULTS: School closures, travel restrictions, community-level lockdown, and contact tracing were introduced concurrently around late January but subsequent epidemic trends differed among provinces. Compared with Hubei, the other five most-affected provinces reported a lower crude case fatality ratio and proportion of critical and severe hospitalised cases. From March 2020, as the local transmission of COVID-19 declined, switching the focus of measures to the testing and quarantine of inbound travellers may have helped to sustain the control of the epidemic. CONCLUSIONS: Aggregated indicators of case notifications and severity distributions are essential for monitoring an epidemic. A publicly available database containing these indicators and information regarding control measures is a useful resource for further research and policy planning in response to the COVID-19 epidemic

Band alignments, valence bands, and core levels in the tin sulfides SnS, SnS2, and Sn2S3:Experiment and Theory

Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photoemission spectroscopy (XPS) and inverse photoemission spectroscopy measurements of single crystal SnS, SnS2, and Sn2S3, with electronic-structure calculations from density functional theory (DFT). Differences in the XPS spectra of the three phases, including a large 0.9 eV shift between the 3d5/2 peak for SnS and SnS2, make this technique useful when identifying phase-pure or mixed-phase systems. Comparison of the valence band spectra from XPS and DFT reveals extra states at the top of the valence bands of SnS and Sn2S3, arising from the hybridization of lone pair electrons in Sn(II), which are not present for Sn(IV), as found in SnS2. This results in relatively low ionization potentials for SnS (4.71 eV) and Sn2S3 (4.66 eV), giving a more comprehensive explanation as to the origin of the poor efficiencies. We also demonstrate, by means of a band alignment, the large band offsets of SnS and Sn2S3 from other photovoltaic materials and highlight the detrimental effect on cell performance of secondary tin sulfide phase formation in SnS and CZTS films

Self-Compensation in Transparent Conducting F-Doped SnO2

The factors limiting the conductivity of fluorine-doped tin dioxide (FTO) produced via atmospheric pressure chemical vapor deposition are investigated. Modeling of the transport properties indicates that the measured Hall effect mobilities are far below the theoretical ionized impurity scattering limit. Significant compensation of donors by acceptors is present with a compensation ratio of 0.5, indicating that for every two donors there is approximately one acceptor. Hybrid density functional theory calculations of defect and impurity formation energies indicate the most probable acceptor-type defects. The fluorine interstitial defect has the lowest formation energy in the degenerate regime of FTO. Fluorine interstitials act as singly charged acceptors at the high Fermi levels corresponding to degenerately n-type films. X-ray photoemission spectroscopy of the fluorine impurities is consistent with the presence of substitutional F O donors and interstitial F i in a roughly 2:1 ratio in agreement with the compensation ratio indicated by the transport modeling. Quantitative analysis through Hall effect, X-ray photoemission spectroscopy, and calibrated secondary ion mass spectrometry further supports the presence of compensating fluorine-related defects