Autonomous motility of polymer films coupled to stimuli gradients

Adaptive soft materials exhibit a diverse set of behaviors including reconfiguration, actuation, and locomotion. These responses are typically optimized in isolation. Here, we explore the interrelation between these behaviors by developing a behavioral phase diagram for hygromorphic polymer films. We determine that the dynamic behaviors are a result of not only a response to, but also an interaction with a humidity gradient, which can be tuned via control of the environment and film characteristics, including size, permeability and coefficient of hygroscopic expansion to target a desired behavior such as multi-modal locomotion. Using the improved understanding of stimuli interactive materials gained from our study of monolithic polymer films, we demonstrate how robust composites can be designed to exhibit autonomous, environmentally-responsive behaviors, and how these concepts can be incorporated into origami structures to engineer the extent and sequence of motions

Thermodynamics of the quantum easy-plane antiferromagnet on the triangular lattice

The classical XXZ triangular-lattice antiferromagnet (TAF) shows both an Ising and a BKT transition, related to the chirality and the in-plane spin components, respectively. In this paper the quantum effects on the thermodynamic quantities are evaluated by means of the pure-quantum self-consistent harmonic approximation (PQSCHA), that allows one to deal with any spin value through classical MC simulations. We report the internal energy, the specific heat, and the in-plane correlation length of the quantum XX0 TAF, for S=1/2, 1, 5/2. The quantum transition temperatures turn out to be smaller the smaller the spin, and agree with the few available theoretical and numerical estimates.Comment: 4 pages,3 postscript figure

Quantum effects on the BKT phase transition of two-dimensional Josephson arrays

The phase diagram of two dimensional Josephson arrays is studied by means of the mapping to the quantum XY model. The quantum effects onto the thermodynamics of the system can be evaluated with quantitative accuracy by a semiclassical method, the {\em pure-quantum self-consistent harmonic approximation}, and those of dissipation can be included in the same framework by the Caldeira-Leggett model. Within this scheme, the critical temperature of the superconductor-to-insulator transition, which is a Berezinskii-Kosterlitz-Thouless one, can be calculated in an extremely easy way as a function of the quantum coupling and of the dissipation mechanism. Previous quantum Monte Carlo results for the same model appear to be rather inaccurate, while the comparison with experimental data leads to conclude that the commonly assumed model is not suitable to describe in detail the real system.Comment: 4 pages, 2 figures, to be published in Phys. Rev.

The two-dimensional quantum Heisenberg antiferromagnet: effective Hamiltonian approach to the thermodynamics

In this paper we present an extensive study of the thermodynamic properties of the two-dimensional quantum Heisenberg antiferromagnet on the square lattice; the problem is tackled by the pure-quantum self-consistent harmonic approximation, previously applied to quantum spin systems with easy-plane anisotropies, modeled to fit the peculiar features of an isotropic system. Internal energy, specific heat, correlation functions, staggered susceptibility, and correlation length are shown for different values of the spin, and compared with the available high-temperature expansion and quantum Monte Carlo results, as well as with the available experimental data.Comment: 14 pages, 13 Postscript figures embedded by psfig.sty; revisions: paper shortened, some parts moved in the appendices, 4 figures replaced by 2 only, minor errors correcte

Emulation of a Target Trial From Observational Data to Compare Effectiveness of Casirivimab/Imdevimab and Bamlanivimab/Etesevimab for Early Treatment of Non-Hospitalized Patients With COVID-19

OBJECTIVES: Comparative analysis between different monoclonal antibodies (mAbs) against SARS-CoV-2 are lacking. We present an emulation trial from observational data to compare effectiveness of Bamlanivimab/Etesevimab (BAM/ETE) and Casirivimab/Imdevimab (CAS/IMD) in outpatients with early mild-to-moderate COVID-19 in a real-world scenario of variants of concern (VoCs) from Alpha to Delta. METHODS: Allocation to treatment was subject to mAbs availability, and the measured factors were not used to determine which combination to use. Patients were followed through day 30. Viral load was measured by cycle threshold (CT) on D1 (baseline) and D7. Primary outcome was time to COVID-19-related hospitalization or death from any cause over days 0-30. Weighted pooled logistic regression and marginal structural Cox model by inverse probability weights were used to compare BAM/ETE vs. CAS/IMD. ANCOVA was used to compare mean D7 CT values by intervention. Models were adjusted for calendar month, MASS score and VoCs. We evaluated effect measure modification by VoCs, vaccination, D1 CT levels and enrolment period. RESULTS: COVID19-related hospitalization or death from any cause occurred in 15 of 237 patients in the BAM/ETE group (6.3%) and in 4 of 196 patients in the CAS/IMD group (2.0%) (relative risk reduction [1 minus the relative risk] 72%; p=0.024). Subset analysis carried no evidence that the effect of the intervention was different across stratification factors. There was no evidence in viral load reduction from baseline through day 7 across the two groups (+0.17, 95% -1.41;+1.74, p=0.83). Among patients who experienced primary outcome, none showed a negative RT-PCR test in nasopharyngeal swab (p=0.009) and 82.4% showed still high viral load (p<0.001) on D7. CONCLUSIONS: In a pre-Omicron epidemiologic scenario, CAS/IMD reduced risk of clinical progression of COVID-19 compared to BAM/ETE. This effect was not associated with a concomitant difference in virological response

SARS-CoV-2 nasopharyngeal viral load in individuals infected with BA.2, compared to Alpha, Gamma, Delta and BA.1 variants: A single-center comparative analysis

BACKGROUND: SARS-CoV-2 has evolved, leading to the emergence of new Variants Of Concern (VOCs) with significant impact on transmissibility. Although the transmission process is complex, higher nasopharyngeal viral load (NP-VL) can be considered as a proxy for greater transmissibility. OBJECTIVES: The aim of this analysis was to compare NP-VL across a set of representative VOCs observed in mildly symptomatic patients. STUDY DESIGN: Observational single-center comparative analysis of patients with early mild-to-moderate COVID-19, enrolled within the early treatment access program of Lazzaro Spallanzani Institute (March 2021-March 2022). NP-VL before drug administration was estimated through RT-PCR, based on cycle threshold values (CTs); VOCs were identified by Sanger sequencing. VOCs’ average treatment effect (ATE) was estimated on the CTs fitted in the log2 scale, controlling for potential confounders. RESULTS: A total of 707 patients were included. VOCs were: 10% Alpha, 3% Gamma, 34% Delta, 34% BA.1, 19% BA.2. Mean CTs for BA.1 and BA.2 were lower than Delta and BA.1, respectively. After adjusting for calendar time, age, immunodeficiency and vaccination, CTs for Gamma were lower than those seen for Alpha and higher than Delta, for Delta were similar to BA.1, for BA.2 were lower than Delta and BA.1. CONCLUSIONS: Our analysis shows higher NP-VL of BA.2 compared to previously circulating VOCs, even after controlling for factors potentially contributing to the amount of nasopharyngeal viral RNA, included vaccination, supporting the increased transmissibility of BA.2. Further studies are necessary to clarify this mechanism and to provide guidance for public health measures

Prophylactic heparin and risk of orotracheal intubation or death in patients with mild or moderate COVID-19 pneumonia

Prophylactic low molecular weight heparin (pLMWH) is currently recommended in COVID-19 to reduce the risk of coagulopathy. The aim of this study was to evaluate whether the antinflammatory effects of pLMWH could translate in lower rate of clinical progression in patients with COVID-19 pneumonia. Patients admitted to a COVID-hospital in Rome with SARS-CoV-2 infection and mild/moderate pneumonia were retrospectively evaluated. The primary endpoint was the time from hospital admission to orotracheal intubation/death (OTI/death). A total of 449 patients were included: 39% female, median age 63 (IQR, 50–77) years. The estimated probability of OTI/death for patients receiving pLMWH was: 9.5% (95% CI 3.2–26.4) by day 20 in those not receiving pLMWH vs. 10.4% (6.7–15.9) in those exposed to pLMWH; p-value = 0.144. This risk associated with the use of pLMWH appeared to vary by PaO_{2}/FiO_{2} ratio aHR 1.40 (95% CI 0.51–3.79) for patients with an admission PaO_{2}/FiO_{2} ≤ 300 mmHg and 0.27 (0.03–2.18) for those with PaO_{2}/FiO_{2} > 300 mmHg; p-value at interaction test 0.16. pLMWH does not seem to reduce the risk of OTI/death mild/moderate COVID-19 pneumonia, especially when respiratory function had already significantly deteriorated. Data from clinical trials comparing the effect of prophylactic vs. therapeutic dosage of LMWH at various stages of COVID-19 disease are needed

Effect of tecovirimat on healing time and viral clearance by emulation of a target trial in patients hospitalized for mpox

Tecovirimat is a treatment option for severe mpox, although randomized clinical trials are ongoing. The aim of the study is to assess the effect of tecovirimat on healing time and the extent of viral clearance by target trial emulation using observational data. Clinical and virological data of patients hospitalized for mpox were collected. Samples from the upper respiratory tract (URT) were grouped in two time points: T1 (median 6 days from symptoms onset) and T2 (median 5 days from T1). Patients were followed-up until recovery. Average treatment effect (ATE) in patients untreated versus treated with tecovirimat was estimated on time to healing and variation in viral load in URT, using a weighted and cloning analysis. Among the 41 patients included, 19 completed a course of tecovirimat. The median time from symptoms onset to hospitalization and to drug-starting was 4 days and 10 days, respectively. No improvement in healing time in treated versus untreated was observed. No difference by treatment group in time to viral clearance was detected by ATE fitted in a subset of 13 patients after controlling for confounders. We found no evidence for a large effect of tecovirimat in shortening healing time and viral clearance. While awaiting the results of randomized studies, the use of tecovirimat should be restricted to the clinical trial setting

No Efficacy of the Combination of Lopinavir/Ritonavir Plus Hydroxychloroquine Versus Standard of Care in Patients Hospitalized With COVID-19: A Non-Randomized Comparison

Objectives: No specific treatment has been approved for COVID-19. Lopinavir/ritonavir (LPV/r) and hydroxychloroquine (HCQ) have been used with poor results, and a trial showed advantages of combined antiviral therapy vs. single antivirals. The aim of the study was to assess the effectiveness of the combination of antivirals (LPV/r and HCQ) or their single use in COVID-19 hospitalized patients vs. standard of care (SoC). Methods: Patients ≥18 years with SARS-CoV-2 infection, defined as positive RT-PCR from nasal/oropharyngeal (NP/OP) swab or positive serology, admitted at L. Spallanzani Institute (Italy) were included. Primary endpoint: time to invasive ventilation/death. Secondary endpoint: time to two consecutive negative SARS-CoV-2 PCRs in NP/OP swabs. In order to control for measured confounders, a marginal Cox regression model with inverse probability weights was used. Results: A total of 590 patients were included in the analysis: 36.3% female, 64 years (IQR 51-76), and 91% with pneumonia. Cumulative probability of invasive ventilation/death at 14 days was 21.2% (95% CI 17.6, 24.7), without difference between SOC, LPV/r, hydroxychloroquine, HCQ + LPV/r, and SoC. The risk of invasive ventilation/death in the groups appeared to vary by baseline ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2). Overall cumulative probability of confirmed negative nasopharyngeal swabs at 14 days was 44.4% (95% CI 38.9, 49.9), without difference between groups. Conclusion: In this retrospective analysis, we found no difference in the rate of invasive ventilation/death or viral shedding by different strategies, as in randomized trials performed to date. Moreover, even the combination HCQ + LPV/r did not show advantages vs. SoC