A global Carleman estimate in a transmission wave equation and application to a one-measurement inverse problem

We consider a transmission wave equation in two embedded domains in $R^2$, where the speed is $a1 > 0$ in the inner domain and $a2 > 0$ in the outer domain. We prove a global Carleman inequality for this problem under the hypothesis that the inner domain is strictly convex and $a1 > a2$ . As a consequence of this inequality, uniqueness and Lip- schitz stability are obtained for the inverse problem of retrieving a stationary potential for the wave equation with Dirichlet data and discontinuous principal coefficient from a single time-dependent Neumann boundary measurement

Tracking health system performance in times of crisis using routine health data: lessons learned from a multicountry consortium

COVID-19 has prompted the use of readily available administrative data to track health system performance in times of crisis and to monitor disruptions in essential healthcare services. In this commentary we describe our experience working with these data and lessons learned across countries. Since April 2020, the Quality Evidence for Health System Transformation (QuEST) network has used administrative data and routine health information systems (RHIS) to assess health system performance during COVID-19 in Chile, Ethiopia, Ghana, Haiti, Lao People's Democratic Republic, Mexico, Nepal, South Africa, Republic of Korea and Thailand. We compiled a large set of indicators related to common health conditions for the purpose of multicountry comparisons. The study compiled 73 indicators. A total of 43% of the indicators compiled pertained to reproductive, maternal, newborn and child health (RMNCH). Only 12% of the indicators were related to hypertension, diabetes or cancer care. We also found few indicators related to mental health services and outcomes within these data systems. Moreover, 72% of the indicators compiled were related to volume of services delivered, 18% to health outcomes and only 10% to the quality of processes of care. While several datasets were complete or near-complete censuses of all health facilities in the country, others excluded some facility types or population groups. In some countries, RHIS did not capture services delivered through non-visit or nonconventional care during COVID-19, such as telemedicine. We propose the following recommendations to improve the analysis of administrative and RHIS data to track health system performance in times of crisis: ensure the scope of health conditions covered is aligned with the burden of disease, increase the number of indicators related to quality of care and health outcomes; incorporate data on nonconventional care such as telehealth; continue improving data quality and expand reporting from private sector facilities; move towards collecting patient-level data through electronic health records to facilitate quality-of-care assessment and equity analyses; implement more resilient and standardized health information technologies; reduce delays and loosen restrictions for researchers to access the data; complement routine data with patient-reported data; and employ mixed methods to better understand the underlying causes of service disruptions

Electrodeposited Polycrystalline Silver Electrodes: Surface Control for Electrocatalysis Studies

An advantageous procedure is developed, allowing prepn. of electrodeposited silver electrodes of highly controlled polycryst. surface (characterized by both electrochem. techniques and SEM), to be employed as cathodes for interphase and electrocatalysis studies. Such electrodes, tested in halide adsorption expts. in parallel with the more demanding single-crystal and polycryst. silver rod ones, acting as a ref., perform competitively in terms of both reproducibility and stability. The same expts. allow further evaluation of the surface roughness factors of the electrodeposited silver electrodes, based on (i) the Parsons-Zobel criterion and (ii) the comparison of their capacitance min. with those of the (110) single-crystal ones, both approaches resulting in very good agreement with the std. UPD and capacitive methods

A screening of carbon-based electrodes (GC, BDD, F-BDD) as non-catalytic reference materials for investigations in organic electrocatalysis

In a systematic cyclovoltammetric investigation of electrochemical organic processes, the electrocatalytic effects of the tested electrode materials (i.e., their ability to lower the activation barrier for the process) are conveniently quantified in terms of difference of the peak potential obtained on the catalytic electrode vs. the peak potential obtained on a cathode free of electrocatalytic effects (for the target process). Glassy carbon (GC), which has often been the favorite electrode material for mechanistic investigations of outer-sphere electron transfer processes, is here compared with as prepared, hydrogen-terminated boron-doped diamond (BDD) and fluorinated boron-doped diamond (F-BDD). They are also carbon-based materials but, to a higher degree, terminated with inert groups possibly preventing specific adsorption. Specifically, the comparison is carried out considering the electrocatalytic reduction of model organic halides. While the current densities are comparable, the reduction potentials are regularly shifted in the negative direction, in the sequence GC < BDD < F-BDD, consistently with the decreasing number of O groups and the increasing number of inert H and/or F atoms, the latter species possibly exerting even a repulsing effect towards the reacting halide adsorption

Surface screening effects by specifically adsorbed halide anions in the electrocatalytic reduction of a model organic halide at mono- and polycrystalline silver in acetonitrile

The silver surface screening effects by specifically adsorbed halide anions in the electrocatalytic reduction of a model organic bromide (acetobromoglucose) have been studied by cyclic voltammetry on controlled mono- and polycrystalline silver surfaces in acetonitrile+0.1 M tetraethylammonium perchlorate medium as a function of the concentration cX of added TEAX (X = Cl, Br, or I, TEA, tetraethylammonium). The reduction peak potentials, Ep, are regularly shifted in the negative direction with increasing cX, typically tending to an asymptotic value for cX 48 0.1 M. Several literature models describing adsorption/desorption equilibria have been applied to justify the above experimental Ep versus c X trends (being logarithmic in the iodide cases) for the three halides and the four silver surfaces tested

The role of surface morphology on the electrocatalytic reduction of organic halides on mono- and polycrystalline silver

The electrocatalytic reduction of organic halides on silver, assumed to hinge on an attenuated radical intermediate R efX efAg, is a reaction of great applicative interest that also provides an example of organic electrocatalytic process particularly convenient for a mechanistic study. The complexity of the problem requires to analyze separately the roles of the many actors involved. The present work focuses on the role of the silver surface morphology, contrasting the reactivity of a series of model halides in systematic CV experiments on (1 1 1), (1 1 0), and (1 0 0) silver monocrystals and on controlled polycrystalline silver surfaces of increasing roughness, in acetonitrile+tetraethylammonium perchlorate medium. The reduction potentials of the alkyl, glycosyl, and benzyl derivatives appear significantly shifted in the positive direction with increasing surface roughness (for polycrystals) or atomic densities and/or surface faceting (for monocrystals) by an extent linked with the molecular structure of the organic halide to be reduced. The addition of strongly specifically adsorbed iodide anions, resulting in surface screening, also results in a leveling effect of the catalytic properties of the different surfaces tested

Building up an electrocatalytic activity scale of cathode materials for organic halide reductions

A wide study on the electrochem. activity of 4 model org. bromides was carried out in MeCN on 9 cathodes of widely different affinity for halide anions (Pt, Zn, Hg, Sn, Bi, Pb, Au, Cu, Ag), and the electrocatalytic activities of the latter were evaluated with respect to 3 possible inert ref. cathode materials, i.e. glassy C, B-doped diamond, and fluorinated B-doped diamond. A general electrocatalytic activity scale for the process is proposed, with a discussion on its modulation by the configuration of the reacting mol., and its connection with thermodn. parameters accounting for halide adsorption

High conductivity and chemical stability of BaCe1-x-yZrxYyO3-delta proton conductors prepared by a sol-gel method

High-temperature proton conductors are promising as electrolytes for intermediate-temperature solid oxide fuel cells. Among them, BaCeO(3)-based materials have high proton conductivity but rather poor chemical stability. In contrast, barium zirconates are rather stable, but have poorly reproducible densities and conductivities. In this study, the investigation of BaCe(1-x-y)Zr(x)Y(y)O(3-delta) solid solutions (x = 0, 0.10, 0.20, 0.30, 0.40; y = 0.15, 0.20) was undertaken, with the final aim of finding a composition having both high conductivity and good stability. The influence of the modified sol-gel Pechini synthetic approach on the powder morphology, and of a barium excess on the densification were demonstrated. Single-phase perovskite powders were prepared and high density pellets were obtained at temperatures lower than those commonly employed. Stability tests demonstrated that the Zr introduction into doped barium cerate greatly enhanced the chemical stability, particularly for Zr >= 20%. The proton conductivities, measured in a humidified H(2)/Ar atmosphere by impedance spectroscopy, were only slightly influenced by the Zr amount. Overall, BaCe(1-x-y)Zr(x)Y(y)O(3-delta) solid solutions having Zr approximate to 20-40% and Y approximate to 15-20% showed good chemical stability and high conductivity