Distinguishing homolytic vs heterolytic bond dissociation of phenylsulfonium cations with localized active space methods.

Modeling chemical reactions with quantum chemical methods is challenging when the electronic structure varies significantly throughout the reaction and when electronic excited states are involved. Multireference methods, such as complete active space self-consistent field (CASSCF), can handle these multiconfigurational situations. However, even if the size of the needed active space is affordable, in many cases, the active space does not change consistently from reactant to product, causing discontinuities in the potential energy surface. The localized active space SCF (LASSCF) is a cheaper alternative to CASSCF for strongly correlated systems with weakly correlated fragments. The method is used for the first time to study a chemical reaction, namely the bond dissociation of a mono-, di-, and triphenylsulfonium cation. LASSCF calculations generate smooth potential energy scans more easily than the corresponding, more computationally expensive CASSCF calculations while predicting similar bond dissociation energies. Our calculations suggest a homolytic bond cleavage for di- and triphenylsulfonium and a heterolytic pathway for monophenylsulfonium.

Quantum Algorithm for Imaginary-Time Green's Functions.

Green's function methods lead to ab initio, systematically improvable simulations of molecules and materials while providing access to multiple experimentally observable properties such as the density of states and the spectral function. The calculation of the exact one-particle Green's function remains a significant challenge for classical computers and was attempted only on very small systems. Here, we present a hybrid quantum-classical algorithm to calculate the imaginary-time one-particle Green's function. The proposed algorithm combines the variational quantum eigensolver and the quantum subspace expansion methods to calculate Green's function in Lehmann's representation. We demonstrate the validity of this algorithm by simulating H2 and H4 on quantum simulators and on IBM's quantum devices.

Inter-observer variability of right ventricular output measurement in newborn infants: an observational study.

Neonatologist Performed Echocardiography (NPE) is one of the emerging technologies used to evaluate Systemic Blood Flow (SBF) in term and preterm infants. Right Ventricular Output (RVO) can assess SBF correctly in the absence of significant interatrial or interventricular shunts, even in the presence of a large patent ductus arteriosus (PDA), but only few studies evaluated inter-observer variability in neonates. Furthermore, measuring pulmonary peak flow (PF) provides a simple screening tool for low SBF state, easier and faster to perform than RVO; no previous studies evaluated PF inter-observer variability. To describe inter-observer variability of RVO and PF measurement in neonates. We conducted a prospective observational study in term and preterm infants admitted to the Neonatal Intensive Care Unit (NICU). Echocardiographic examinations were performed by two expert neonatologists, blinded to each other. Recordings were analyzed off-line to assess RVO and PF variability between observers. We analyzed a cohort of 33 neonates, 17 of them born prematurely. Inter-observer mean difference for RVO was 22,1 mL/kg/min (p = 0.005); the biggest discrepancy was due to pulmonary valve diameter measurement (p = 0.0001). Inter-observer mean difference for PF measurement was not statistically significant. We found a statistically significant inter-observer variability for RVO measurement, consistent with previous reports; PF instead showed low inter-observer variability. For this reason, PF could be evaluated in future studies as a surrogate for RVO in both term and preterm infants, especially in emergency conditions or in presence of a poor echocardiographic window.

Bridging physical intuition and hardware efficiency for correlated electronic states: the local unitary cluster Jastrow ansatz for electronic structure.

A prominent goal in quantum chemistry is to solve the molecular electronic structure problem for ground state energy with high accuracy. While classical quantum chemistry is a relatively mature field, the accurate and scalable prediction of strongly correlated states found, e.g., in bond breaking and polynuclear transition metal compounds remains an open problem. Within the context of a variational quantum eigensolver, we propose a new family of ansatzes which provides a more physically appropriate description of strongly correlated electrons than a unitary coupled cluster with single and double excitations (qUCCSD), with vastly reduced quantum resource requirements. Specifically, we present a set of local approximations to the unitary cluster Jastrow wavefunction motivated by Hubbard physics. As in the case of qUCCSD, exactly computing the energy scales factorially with system size on classical computers but polynomially on quantum devices. The local unitary cluster Jastrow ansatz removes the need for SWAP gates, can be tailored to arbitrary qubit topologies (e.g., square, hex, and heavy-hex), and is well-suited to take advantage of continuous sets of quantum gates recently realized on superconducting devices with tunable couplers. The proposed family of ansatzes demonstrates that hardware efficiency and physical transparency are not mutually exclusive; indeed, chemical and physical intuition regarding electron correlation can illuminate a useful path towards hardware-friendly quantum circuits.

Quantum-enhanced Markov chain Monte Carlo.

Quantum computers promise to solve certain computational problems much faster than classical computers. However, current quantum processors are limited by their modest size and appreciable error rates. Recent efforts to demonstrate quantum speedups have therefore focused on problems that are both classically hard and naturally suited to current quantum hardware, such as sampling from complicated-although not explicitly useful-probability distributions1-3. Here we introduce and experimentally demonstrate a quantum algorithm that is similarly well suited to current hardware, but which samples from complicated distributions arising in several applications. The algorithm performs Markov chain Monte Carlo (MCMC), a prominent iterative technique4, to sample from the Boltzmann distribution of classical Ising models. Unlike most near-term quantum algorithms, ours provably converges to the correct distribution, despite being hard to simulate classically. But like most MCMC algorithms, its convergence rate is difficult to establish theoretically, so we instead analysed it through both experiments and simulations. In experiments, our quantum algorithm converged in fewer iterations than common classical MCMC alternatives, suggesting unusual robustness to noise. In simulations, we observed a polynomial speedup between cubic and quartic over such alternatives. This empirical speedup, should it persist to larger scales, could ease computational bottlenecks posed by this sampling problem in machine learning5, statistical physics6 and optimization7. This algorithm therefore opens a new path for quantum computers to solve useful-not merely difficult-sampling problems.

Use of Cryoprecipitate in Newborn Infants.

Cryoprecipitate is a transfusion blood product derived from fresh-frozen plasma (FFP), comprised mainly of the insoluble precipitate that gravitates to the bottom of the container when plasma is thawed and refrozen. It is highly enriched in coagulation factors I (fibrinogen), VIII, and XIII; von Willebrand factor (vWF); and fibronectin. In this article, we have reviewed currently available information on the preparation, properties, and clinical importance of cryoprecipitate in treating critically ill neonates. We have searched extensively in the databases PubMed, Embase, and Scopus after short-listing keywords to describe the current relevance of cryoprecipitate.

Hierarchical Clifford Transformations to Reduce Entanglement in Quantum Chemistry Wave Functions.

The performance of computational methods for many-body physics and chemistry is strongly dependent on the choice of the basis used to formulate the problem. Hence, the search for similarity transformations that yield better bases is important for progress in the field. So far, tools from theoretical quantum information have not been thoroughly explored for this task. Here we take a step in this direction by presenting efficiently computable Clifford similarity transformations for the molecular electronic structure Hamiltonian, which expose bases with reduced entanglement in the corresponding molecular ground states. These transformations are constructed via block-diagonalization of a hierarchy of truncated molecular Hamiltonians, preserving the full spectrum of the original problem. We show that the bases introduced here allow for more efficient classical and quantum computations of ground-state properties. First, we find a systematic reduction of bipartite entanglement in molecular ground states as compared to standard problem representations. This entanglement reduction has implications in classical numerical methods, such as those based on the density matrix renormalization group. Then, we develop variational quantum algorithms that exploit the structure in the new bases, showing again improved results when the hierarchical Clifford transformations are used.

Challenges in the Use of Quantum Computing Hardware-Efficient Ansätze in Electronic Structure Theory.

Advances in quantum computation for electronic structure, and particularly heuristic quantum algorithms, create an ongoing need to characterize the performance and limitations of these methods. Here we discuss some potential pitfalls connected with the use of hardware-efficient Ansätze in variational quantum simulations of electronic structure. We illustrate that hardware-efficient Ansätze may break Hamiltonian symmetries and yield nondifferentiable potential energy curves, in addition to the well-known difficulty of optimizing variational parameters. We discuss the interplay between these limitations by carrying out a comparative analysis of hardware-efficient Ansätze versus unitary coupled cluster and full configuration interaction, and of second- and first-quantization strategies to encode Fermionic degrees of freedom to qubits. Our analysis should be useful in understanding potential limitations and in identifying possible areas of improvement in hardware-efficient Ansätze.

Quantum chemistry simulation of ground- and excited-state properties of the sulfonium cation on a superconducting quantum processor.

The computational description of correlated electronic structure, and particularly of excited states of many-electron systems, is an anticipated application for quantum devices. An important ramification is to determine the dominant molecular fragmentation pathways in photo-dissociation experiments of light-sensitive compounds, like sulfonium-based photo-acid generators used in photolithography. Here we simulate the static and dynamical electronic structure of the H3S+ molecule, taken as a minimal model of a triply-bonded sulfur cation, on a superconducting quantum processor of the IBM Falcon architecture. To this end, we generalize a qubit reduction technique termed entanglement forging or EF [A. Eddins et al., Phys. Rev. X Quantum, 2022, 3, 010309], currently restricted to the evaluation of ground-state energies, to the treatment of molecular properties. While in a conventional quantum simulation a qubit represents a spin-orbital, within EF a qubit represents a spatial orbital, reducing the number of required qubits by half. We combine the generalized EF with quantum subspace expansion [W. Colless et al., Phys. Rev. X, 2018, 8, 011021], a technique used to project the time-independent Schrodinger equation for ground- and excited-states in a subspace. To enable experimental demonstration of this algorithmic workflow, we deploy a sequence of error-mitigation techniques. We compute dipole structure factors and partial atomic charges along ground- and excited-state potential energy curves, revealing the occurrence of homo- and heterolytic fragmentation. This study is an important step towards the computational description of photo-dissociation on near-term quantum devices, as it can be generalized to other photodissociation processes and naturally extended in different ways to achieve more realistic simulations.

N-Electron Valence Perturbation Theory with Reference Wave Functions from Quantum Computing: Application to the Relative Stability of Hydroxide Anion and Hydroxyl Radical.

Quantum simulations of the hydroxide anion and hydroxyl radical are reported, employing variational quantum algorithms for near-term quantum devices. The energy of each species is calculated along the dissociation curve, to obtain information about the stability of the molecular species being investigated. It is shown that simulations restricted to valence spaces incorrectly predict the hydroxyl radical to be more stable than the hydroxide anion. Inclusion of dynamical electron correlation from nonvalence orbitals is demonstrated, through the integration of the variational quantum eigensolver and quantum subspace expansion methods in the workflow of N-electron valence perturbation theory, and shown to correctly predict the hydroxide anion to be more stable than the hydroxyl radical, provided that basis sets with diffuse orbitals are also employed. Finally, we calculate the electron affinity of the hydroxyl radical using an aug-cc-pVQZ basis on IBM's quantum devices.

Long peripheral catheters in neonates: filling the gap between short peripheral catheters and epicutaneous-caval catheters?

INTRODUCTION: Non-critically ill neonates at times require venous access to provide peripherally compatible infusions for a limited period (more than 3 days). In such a situation, short peripheral cannulas are not appropriate as their average duration is about 2 days, while-on the other hand-epicutaneous-caval catheters may be too invasive. In these patients, insertion of long peripheral cannulas may be an effective option. METHODS: In this observational retrospective study, we revised all "long" peripheral catheters (4 and 6 cm long) inserted by direct Seldinger technique in our neonatal intensive care unit when peripheral venous access was required for more than 3 days. RESULTS: We inserted 52 2Fr polyurethane catheters, either 4 cm long (n = 25) or 6 cm long (n = 27) in 52 patients. Mean dwelling time was 4.17 days (range 1-12). Most devices were inserted in the cephalic vein (n = 18, 35%), and the rest in the saphenous vein (n = 11, 21%) and other superficial veins. There was no significant correlation between the duration of the device and type of infusion (p = 0.40). The main complications were infiltration (n = 16, 31%) and phlebitis (n = 8, 15%). The rate of removal due to complications was significantly higher (p < 0.01) in neonates with bodyweight <2000 g at the time of insertion. CONCLUSION: In our experience, 2 Fr 4-6 cm long peripheral catheters may be a valid option for neonates requiring peripherally compatible infusions for more than 3 days. The limits of this study are the necessity of training in the technique of insertion and the small size of our sample. The longest dwell was observed in neonates weighing >2000 g at the time of LPC insertion.

Prenatal maternal stress during the COVID-19 pandemic and infant regulatory capacity at 3 months: A longitudinal study.

The COVID-19 pandemic is a global traumatic experience for citizens, especially during sensitive time windows of heightened plasticity such as pregnancy and neonatal life. Pandemic-related stress experienced by mothers during pregnancy may act as an early risk factor for infants' regulatory capacity development by altering maternal psychosocial well-being (e.g., increased anxiety, reduced social support) and caregiving environment (e.g., greater parenting stress, impaired mother-infant bonding). The aim of the present longitudinal study was to assess the consequences of pandemic-related prenatal stress on infants' regulatory capacity. A sample of 163 mother-infant dyads was enrolled at eight maternity units in northern Italy. They provided complete data about prenatal stress, perceived social support, postnatal anxiety symptoms, parenting stress, mother-infant bonding, and infants' regulatory capacity at 3 months of age. Women who experienced emotional stress and received partial social support during pregnancy reported higher anxious symptoms. Moreover, maternal postnatal anxiety was indirectly linked to the infants' regulatory capacity at 3 months, mediated by parenting stress and mother-infant bonding. Dedicated preventive interventions should be delivered to mothers and should be focused on protecting the mother-infant dyad from the detrimental effects of pandemic-related stress during the COVID-19 healthcare emergency.

Fresh Frozen Plasma Administration in the NICU: Evidence-based Guidelines.

The use of FFP in neonatology should be primarily for neonates with active bleeding and associated coagulopathy. However, since there is limited and poor-quality evidence supporting neonatal FFP transfusion, considerable FFP usage continues to be outside of this recommendation, as documented by neonatal transfusion audits. This review updates the scientific evidence available on FFP use in neonatology and reports the best evidence-practice for the safety of neonates receiving FFP.

Use of Fresh-frozen Plasma in Newborn Infants.

Nearly 10% of premature and critically ill infants receive fresh-frozen plasma (FFP) transfusions to reduce their high risk of bleeding. The authors have only limited data to identify relevant clinical predictors of bleeding and to evaluate the efficacy of FFP administration. There is still no consensus on the optimal use of FFP in infants who have abnormal coagulation parameters but are not having active bleeding. The aims of this review are to present current evidence derived from clinical studies focused on the use of FFP in neonatology and then use these data to propose best practice recommendations for the safety of neonates receiving FFP.

Enteroviral Infections in Infants.

Enteroviruses (EVs) are major pathogens in young infants. These viruses were traditionally classified into the following four subgenera: polio, coxsackie A and B, and echoviruses. Now that poliomyelitis seems to be controlled in most parts of the world, coxsackie and echoviruses are gaining more attention because (i) the structural and pathophysiological similarities and (ii) the consequent possibilities in translational medicine. Enteroviruses are transmitted mainly by oral and fecal-oral routes; the clinical manifestations include a viral prodrome including fever, feeding intolerance, and lethargy, which may be followed by exanthema; aseptic meningitis and encephalitis; pleurodynia; myopericarditis; and multi-system organ failure. Laboratory diagnosis is largely based on reverse transcriptase-polymerase chain reaction, cell culture, and serology. Prevention and treatment can be achieved using vaccination, and administration of immunoglobulins and antiviral drugs. In this article, we have reviewed the properties of these viruses, their clinical manifestations, and currently available methods of detection, treatment, and prognosis.

Post-partum Women's Anxiety and Parenting Stress: Home-Visiting Protective Effect During the COVID-19 Pandemic.

OBJECTIVES: The COVID-19 pandemic resulted in a particularly adverse and stressful environment for expecting mothers, possibly enhancing feelings of anxiety and parenting stress. The present work assesses mothers' anxiety levels at delivery and parenting stress after 3 months as moderated by home-visiting sessions. METHODS: Women (n = 177) in their second or third trimester of pregnancy during the COVID-19 lockdown were enrolled in northern Italy and split into those who did and did not receive home visits. After 3 months, the association between anxiety at delivery and parenting stress was assessed with bivariate correlations in the whole sample and comparing the two groups. RESULTS: Higher anxiety at birth correlated with greater perceived stress after 3 months. Mothers who received at least one home-visiting session reported lower parenting stress at 3 months than counterparts who did not receive home visits. CONCLUSIONS FOR PRACTICE: The perinatal period is a sensitive time window for mother-infant health, especially during a critical time like the COVID-19 pandemic. We suggest that home-visiting programs could be beneficial during global healthcare emergencies to promote maternal well-being after delivery.