Thrombolysis and bridging therapy in patients with acute ischaemic stroke and Covid-19.

BACKGROUND AND PURPOSE: Comorbidity of acute ischaemic stroke with Covid-19 is a challenging condition, potentially influencing the decision of whether to administer intravenous thrombolysis (IVT). We aimed to assess the 1-month outcome in ischaemic stroke patients with Covid-19 infection who received IVT alone or before thrombectomy (bridging therapy). METHODS: As a collaboration initiative promoted by the Italian Stroke Organization, all Italian stroke units (n = 190) were contacted and invited to participate in data collection on stroke patients with Covid-19 who received IVT. RESULTS: Seventy-five invited centers agreed to participate. Thirty patients received IVT alone and 17 received bridging therapy between 21 February 2020 and 30 April 2020 in 20 centers (n = 18, Northern Italy; n = 2, Central Italy). At 1 month, 14 (30.4%) patients died and 20 (62.5%) survivors had a modified Rankin Scale (mRS) score of 3 to 5. At 24 to 36 hours, asymptomatic intracerebral hemorrhage (ICH) was reported in eight (17.4%) patients and symptomatic ICH (sICH) in two (4.3%) patients. Causes of death were severe ischaemic stroke (n = 8), a new ischaemic stroke (n = 2), acute respiratory failure (n = 1), acute renal failure (n = 1), acute myocardial infarction (n = 1), and endocarditis (n = 1). In survivors with a 1-month mRS score of 3 to 5, baseline glucose level was higher, whereas endovascular procedure time in cases of bridging therapy was longer. Baseline National Institutes of Health Stroke Scale glucose and creatinine levels were higher in patients who died. CONCLUSIONS: Intravenous thrombolysis for patients with stroke and Covid-19 was not a rare event in the most affected areas by pandemic, and rates of 1-month unfavorable outcomes were high compared to previous data from the pre-Covid-19 literature. However, risk of sICH was not increased.

First-Principles Nonequilibrium Green's Function Approach to Ultrafast Charge Migration in Glycine.

We investigate the photoinduced ultrafast charge migration phenomenon in the glycine molecule using a recently proposed nonequilibrium Green's functions (NEGF) approach. We first consider the dynamics resulting from the sudden removal of an electron in the valence shells, finding a satisfactory agreement with available data. Then we explicitly simulate the laser-induced photoionization process and study the evolution of the system after the pulse. We disentangle polarization and correlation effects in the electron dynamics and assign the main frequencies to specific elements of the reduced one-particle density matrix. We show that electronic correlations renormalize the bare frequencies, redistribute the spectral weights, and give rise to new spectral features.

Many-body perturbation theory calculations using the yambo code.

yambo is an open source project aimed at studying excited state properties of condensed matter systems from first principles using many-body methods. As input, yambo requires ground state electronic structure data as computed by density functional theory codes such as Quantum ESPRESSO and Abinit. yambo's capabilities include the calculation of linear response quantities (both independent-particle and including electron-hole interactions), quasi-particle corrections based on the GW formalism, optical absorption, and other spectroscopic quantities. Here we describe recent developments ranging from the inclusion of important but oft-neglected physical effects such as electron-phonon interactions to the implementation of a real-time propagation scheme for simulating linear and non-linear optical properties. Improvements to numerical algorithms and the user interface are outlined. Particular emphasis is given to the new and efficient parallel structure that makes it possible to exploit modern high performance computing architectures. Finally, we demonstrate the possibility to automate workflows by interfacing with the yambopy and AiiDA software tools.

Ultrafast Charge Migration in XUV Photoexcited Phenylalanine: A First-Principles Study Based on Real-Time Nonequilibrium Green's Functions.

The early-stage density oscillations of the electronic charge in molecules irradiated by an attosecond XUV pulse takes place on femto- or subfemtosecond time scales. This ultrafast charge migration process is a central topic in attoscience because it dictates the relaxation pathways of the molecular structure. A predictive quantum theory of ultrafast charge migration should incorporate the atomistic details of the molecule, electronic correlations, and the multitude of ionization channels activated by the broad-bandwidth XUV pulse. We propose a first-principles nonequilibrium Green's function method fulfilling all three requirements and apply it to a recent experiment on the photoexcited phenylalanine amino acid. Our results show that dynamical correlations are necessary for a quantitative overall agreement with the experimental data. In particular, we are able to capture the transient oscillations at frequencies 0.15 and 0.30 PHz in the hole density of the amine group as well as their suppression and the concomitant development of a new oscillation at frequency 0.25 PHz after ∼14 fs.

Double excitations in finite systems.

Time-dependent density-functional theory (TDDFT) is widely used in the study of linear response properties of finite systems. However, there are difficulties in properly describing excited states, which have double- and higher-excitation characters, which are particularly important in molecules with an open-shell ground state. These states would be described if the exact TDDFT kernel were used; however, within the adiabatic approximation to the exchange-correlation (xc) kernel, the calculated excitation energies have a strict single-excitation character and are fewer than the real ones. A frequency-dependent xc kernel could create extra poles in the response function, which would describe states with a multiple-excitation character. We introduce a frequency-dependent xc kernel, which can reproduce, within TDDFT, double excitations in finite systems. In order to achieve this, we use the Bethe-Salpeter equation with a dynamically screened Coulomb interaction W(omega), which can describe these excitations, and from this we obtain the xc kernel. Using a two-electron model system, we show that the frequency dependence of W does indeed introduce the double excitations that are instead absent in any static approximation of the electron-hole screening.