Does nosocomial SARS-CoV-2 infection result in increased 30-day mortality? A multi-centre observational study to identify risk factors for worse outcomes in COVID-19 disease

We aimed to determine whether nosocomial SARS-CoV-2 infection has worse outcomes than community-acquired disease. This was prospective cohort study of all hospitalised patients in three acute hospitals with confirmed COVID-19 on 9th April 2020. Patients were followed up for at least 30 days. Nosocomial infection was defined as a positive swab after 7 days of admission. 173 patients were identified; 19 (11.0%) had nosocomial infection. 32 (18.5%) had 30-day all-cause mortality; there was no statistically significant differences between 30-day mortality (21.1% vs 17.6% vs 21.6% respectively, p=0.755). Nosocomial SARS-CoV-2 infection is not associated with increased mortality compared with community acquired infection

Angiotensin converting enzyme inhibitors do not increase the risk of poor outcomes in COVID-19 disease. A multi-centre observational study

Background and aims Hypertension is associated with an increased risk of severe outcomes with COVID-19 disease. Angiotensin Converting Enzyme (ACE) inhibitors are widely used as a first line medication for the treatment of hypertension in the UK, although their use was suggested in early reports to increase the risk associated with SARS-CoV-2 infection. Methods A prospective cohort study of hospitalised patients with laboratory confirmed COVID-19 was conducted across three hospital sites with patients identified on the 9th April 2020. Demographic and other baseline data were extracted from electronic case records, and patients grouped depending on ACE inhibitor usage or not. The 60-day all-cause mortality and need for intubation compared. Results Of the 173 patients identified, 88 (50.8%) had hypertension. Of these 27 (30.7%) used ACE inhibitors. We did not find significant differences in 60-day all-cause mortality, the requirement for invasive ventilation or length of stay between our patient cohorts after adjusting for covariates. Conclusion This study contributes to the growing evidence supporting the continued use of ACE inhibitors in COVID-19 disease, although adequately powered randomised controlled trials will be needed to confirm effects

Atom capture by nanotube and scaling anomaly

The existence of bound state of the polarizable neutral atom in the inverse square potential created by the electric field of single walled charged carbon nanotube (SWNT) is shown to be theoretically possible. The consideration of inequivalent boundary conditions due to self-adjoint extensions lead to this nontrivial bound state solution. It is also shown that the scaling anomaly is responsible for the existence of bound state. Binding of the polarizable atoms in the coupling constant interval \eta^2\in[0,1) may be responsible for the smearing of the edge of steps in quantized conductance, which has not been considered so far in literature.Comment: Accepted in Int.J.Theor.Phy

Normal mode analysis for scalar fields in BTZ black hole background

We analyze the possibility of inequivalent boundary conditions for a scalar field propagating in the BTZ black hole space-time. We find that for certain ranges of the black hole parameters, the Klein-Gordon operator admits a one-parameter family of self-adjoint extensions. For this range, the BTZ space-time is not quantum mechanically complete. We suggest a physically motivated method for determining the spectra of the Klein-Gordon operator.Comment: 6 pages, no figure, late

Finite-temperature Fermi-edge singularity in tunneling studied using random telegraph signals

We show that random telegraph signals in metal-oxide-silicon transistors at millikelvin temperatures provide a powerful means of investigating tunneling between a two-dimensional electron gas and a single defect state. The tunneling rate shows a peak when the defect level lines up with the Fermi energy, in excellent agreement with theory of the Fermi-edge singularity at finite temperature. This theory also indicates that defect levels are the origin of the dissipative two-state systems observed previously in similar devices.Comment: 5 pages, REVTEX, 3 postscript figures included with epsfi

Molecular transport calculations with Wannier functions

We present a scheme for calculating coherent electron transport in atomic-scale contacts. The method combines a formally exact Green's function formalism with a mean-field description of the electronic structure based on the Kohn-Sham scheme of density functional theory. We use an accurate plane-wave electronic structure method to calculate the eigenstates which are subsequently transformed into a set of localized Wannier functions (WFs). The WFs provide a highly efficient basis set which at the same time is well suited for analysis due to the chemical information contained in the WFs. The method is applied to a hydrogen molecule in an infinite Pt wire and a benzene-dithiol (BDT) molecule between Au(111) surfaces. We show that the transmission function of BDT in a wide energy window around the Fermi level can be completely accounted for by only two molecular orbitals.Comment: 15 pages, 12 figures, submitted to Chemical Physic

Donor Centers and Absorption Spectra in Quantum Dots

We have studied the electronic properties and optical absorption spectra of three different cases of donor centers, D^{0}, D^{-} and D^{2-}, which are subjected to a perpendicular magnetic field, using the exact diagonalization method. The energies of the lowest lying states are obtained as function of the applied magnetic field strength B and the distance zeta between the positive ion and the confinement xy-plane. Our calculations indicate that the positive ion induces transitions in the ground-state, which can be observed clearly in the absorption spectra, but as zeta goes to 0 the strength of the applied magnetic field needed for a transition to occur tends to infinity.Comment: 5 pages, 4 figures, REVTeX 4, gzipped tar fil

Novel mechanistic view of catalytic ozonation of gaseous toluene by dual-site kinetic modelling

The catalytic ozonation of VOCs is a promising approach for degradation of indoor VOCs, such as gaseous toluene. However, the mechanism and relevant kinetic steps involved in this reaction remain unclear. In this study, the catalytic ozonation of toluene over MnO2/graphene was investigated using the empirical power law model and classic Langmuir-Hinshelwood single-site (denoted as L-Hs) mechanism. The apparent activation energy determined using the power law model was 29.3±2.5 kJ mol−1. This finding indicated that the catalytic ozonation of toluene over MnO2/graphene was a heterogeneous reaction, and the Langmuir-Hinshelwood mechanism was applicable. However, the L-Hs mechanism did not fit the experimental data, suggesting that the reaction was non-single-site governed. A novel Langmuir-Hinshelwood dual-site (denoted as L-Hd) mechanism was then proposed to explain the experimental observations of the catalytic ozonation of toluene over MnO2/graphene through a steady-state kinetic study. This mechanism was based on the hypothesis that MnO2 was responsible for ozone decomposition and toluene adsorption on graphene; these two types of adsorption were coupled by an adjacent attack. Furthermore, XPS results confirmed the presence of a strong connection between MnO2 and graphene sites on the surface of MnO2/graphene. This connection allowed the adjacent attack and validated the dual-site mechanism. The L-Hd model was consistent with the predicted reaction rate of toluene removal with a correlation coefficient near unity (r2 = 0.9165). Moreover, the physical criterion was in accordance with both enthalpy and entropy of toluene adsorption constraints. Fulfillment of mathematical and physical criteria indicated the catalytic ozonation of toluene over MnO2/graphene can be well described by the L-Hd mechanism. This study helps understand the catalytic ozonation of toluene over MnO2/graphene in a closely mechanistic view

Green function techniques in the treatment of quantum transport at the molecular scale

The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics

Visual Social Media Use Moderates the Relationship between Initial Problematic Internet Use and Later Narcissism

Background: Little is known about the temporal directionality of relationships between problematic internet use and personality disorders such as narcissism. Objective: Although these two constructs are related at a single time, no existent study has determined whether initial problematic internet use is more strongly associated with subsequent narcissism, or vice versa. So, the aim of the research is to verify if problematic internet use predicts the narcissism or vice versa. Methods: Seventy-four university student participants were studied over a four-month period, and completed the Narcissism Personality Inventory, and Problematic Internet Use Questionnaire, at baseline and follow-up. Results: The results demonstrated a relationship between problematic internet use and narcissism at baseline. Time-lagged correlations demonstrated that problematic internet use at baseline was positively related to narcissism four-months later, but not vice versa for social media users whose use was primarily visual. This relationship did not hold for social media users whose use was primarily verbal. Conclusion: These results suggest that problematic internet use may serve to discharge narcissistic personality traits for those who use social media in a visual way, but not for those who do not engage in that form of internet use