Dentists' Perceptions of Personal Infection Control Measurements in Response to COVID-19.

OBJECTIVE: To explore through focus groups (FGs) the perceptions of dental practitioners (DPs) from different countries of the challenges of implementing coronavirus disease 2019 (COVID-19) related biosafety measures, especially personal protection equipment (PPE), during the COVID-19 pandemic period. METHODS: DPs from Colombia, Germany, the United Kingdom, and the United States were invited to participate in country-based FGs. These were facilitated by an experienced moderator who explored the factors that guided the implementation of COVID-19 related biosafety measures and PPE use. Data were analyzed through thematic analysis on the basis of categories defined by the researchers deductively and inductively. RESULTS: A total of 25 DPs participated in 3 FGs (Colombia:n = 8; United Kingdom: n = 7; United States: n = 9) and 1 in an in-depth interview (Germany). DPs described using several processes to judge which guidance document to adopt and which aspects of the guidance were important in their practice. These included making judgments concerning the views of any indemnity organization to which the DPs were responsible, the staff's views in the practice, and the views of patients. In the absence of a single overarching guidance document, DPs filtered the available information through several considerations to find a level of PPE that they deemed "implementable" in local practice. CONCLUSIONS: The findings suggest that the implementation of evidence-based practice is subject to modification through a lens of what is "feasible" in practice. KNOWLEDGE TRANSFER STATEMENT: Clinicians, educators, and policy makers can use the results of this study to understand the process through which guidance is transformed into implementable patient care pathways in the dental practice.

Revealing the short-range structure of the mirror nuclei 3H and 3He.

When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure1-3, and mapping out the strength and the isospin structure (neutron-proton (np) versus proton-proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements3-5. Two-nucleon knockout or 'triple coincidence' reactions have been used to measure the relative contribution of np-SRCs and pp-SRCs by knocking out a proton from the SRC and detecting its partner nucleon (proton or neutron). These measurements6-8 have shown that SRCs are almost exclusively np pairs, but they had limited statistics and required large model-dependent final-state interaction corrections. Here we report on measurements using inclusive scattering from the mirror nuclei hydrogen-3 and helium-3 to extract the np/pp ratio of SRCs in systems with a mass number of three. We obtain a measure of the np/pp SRC ratio that is an order of magnitude more precise than previous experiments, and find a marked deviation from the near-total np dominance observed in heavy nuclei. This result implies an unexpected structure in the high-momentum wavefunction for hydrogen-3 and helium-3. Understanding these results will improve our understanding of the short-range part of the nucleon-nucleon interaction.

Analysis of the Direct Cost of Medical and Surgical Care for Testicular Cancer in Early and Advanced Stages in a Third Level Medical Facility of the Mexican Social Security Institute

Background: The testicular cancer prevails in the third decade of life, the care cost increases with higher staging of the disease. Objective: Compare the direct costs of medical and surgical attention for testicular cancer in early and advanced stages in a Third Level Medical Facility. Material and Methods: Process study, direct costs of medical attention are evaluated. Number of laboratory studies, imaging studies, and medical and surgical treatment were analyzed. The patients were divided into 2 groups: group 1 early stages and group 2 advanced stages. Mann Whitney U test was used for the difference between groups. Results: There were 10 patients in each group, Group 1: 8 (80%) seminomas and 2 (20%) non-seminoma, Group 2: 4 (40%) seminomas and 6 (60%) non-seminomas. The average cost of care in Group 2 is higher than in Group 1, 288,827.90 and 145,911.70 Mexican pesos respectively (p=0.00578). Conclusions: The direct cost of medical attention is higher in the advanced stages compared to the early stages (AU)

Objetivo: Comparar los costes directos de atenciónmédica y quirúrgica del cáncer testicular en etapa tempranay avanzada en un hospital de tercer nivel.Material y Métodos: Estudio de proceso, se evalúancostes directos de atención médica. Se analizaron númerode estudios de laboratorio, gabinete y tratamiento médico yquirúrgico. Los pacientes se dividieron en 2 grupos: grupo1 estadios tempranos y grupo 2 estadios avanzados. Se utilizó la prueba de U de Mann Whitney para diferencia entregrupos.Resultados: Fueron 10 pacientes en cada grupo,Grupo 1: 8 (80%) seminomas y 2 (20%) no seminomas,Grupo 2: 4 (40%) seminomas y 6 (60%) no seminomas. Elcoste promedio de atención en el Grupo 2 es mayor que enel Grupo 1, $288,827.90 y $145,911.70 pesos mexicanosrespectivamente (p=0.00578).Conclusiones: El coste directo de atención médica esmayor en los estadios avanzados comparado con los estadios tempranos. (AU)

Optical interferometry-based array of seafloor environmental sensors using a transoceanic submarine cable.

Optical fiber-based sensing technology can drastically improve Earth observations by enabling the use of existing submarine communication cables as seafloor sensors. Previous interferometric and polarization-based techniques demonstrated environmental sensing over cable lengths up to 10,500 kilometers. However, measurements were limited to the integrated changes over the entire length of the cable. We demonstrate the detection of earthquakes and ocean signals on individual spans between repeaters of a 5860-kilometer-long transatlantic cable rather than the whole cable. By applying this technique to the existing undersea communication cables, which have a repeater-to-repeater span length of 45 to 90 kilometers, the largely unmonitored ocean floor could be instrumented with thousands of permanent real-time environmental sensors without changes to the underwater infrastructure.

Porphyromonas gingivalis outer membrane vesicles modulate cytokine and chemokine production by gingipain-dependent mechanisms in human macrophages.

OBJECTIVE: The aim was to determine the changes of inflammatory mediator expression in human macrophages stimulated with outer membrane vesicles purified from Porphyromonas gingivalis. DESIGN: outer membrane vesicles purified by ultracentrifugation from ATCC 33277 and W83 P. gingivalis strains were used for stimulating human macrophages and determine their inflammatory mediator expression changes. U937 monocyte cells line were differentiated into macrophages and stimulated with outer membrane vesicles for 30 min and six hours. In Independent experiments, the outer membrane vesicles and viable bacteria control were pre-treated with the gingipain inhibitors KYT-1 and KYT-36 (Arg-gingipain and Lys-gingipain, respectively) or Polymyxin-B to block the lipopolysaccharide activity to evaluate the secretion changes of immune mediators IL-1ß, IL-6, TNF-α, IL-8, MCP-1, MIP-1α and RANTES by flow cytometry. A factorial ANOVA was used to analyze the data. RESULTS: The outer membrane vesicles of P. gingivalis ATCC 33277 displayed higher Arg-gingipain activity than those obtained from the P. gingivalis W83 strain (0.6 U/µg vs. 0.46 U/µg). Although the outer membrane vesicles of P. gingivalis stimulated the production of cytokines and chemokines, specific Arg-gingipain and Lys-gingipain inhibition induced significant increases in IL-1ß, IL-6, IL-8, MCP-1, and RANTES levels, and this induction was significantly greater at 6 h compared to 30 min (*p < 0.05). On the contrary, TNF-α secretion decreased when gingipains were blocked. CONCLUSIONS: outer membrane vesicles may play a dual role during P. gingivalis infection based on their ability to induce changes in the immune responses of human macrophages, probably via gingipain-dependent events.

Measurement of the Nucleon F_{2}

The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio. The results, which cover the Bjorken scaling variable range 0.19

Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering.

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75 (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8 (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

Probing Few-Body Nuclear Dynamics via

We report the first measurement of the (e,e^{'}p) three-body breakup reaction cross sections in helium-3 (^{3}He) and tritium (^{3}H) at large momentum transfer [⟨Q^{2}⟩≈1.9 (GeV/c)^{2}] and x_{B}>1 kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta 40≤p_{miss}≤500 MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab initio calculations. Overall good agreement, within ±20%, is observed between data and calculations for the full p_{miss} range for ^{3}H and for 100≤p_{miss}≤350 MeV/c for ^{3}He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at p_{miss}>250 MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of ^{3}He plus ^{3}H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire p_{miss} range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of 500 MeV/c.

Approaching boiling point stability of an alcohol dehydrogenase through computationally-guided enzyme engineering.

Enzyme instability is an important limitation for the investigation and application of enzymes. Therefore, methods to rapidly and effectively improve enzyme stability are highly appealing. In this study we applied a computational method (FRESCO) to guide the engineering of an alcohol dehydrogenase. Of the 177 selected mutations, 25 mutations brought about a significant increase in apparent melting temperature (ΔTm ≥ +3 °C). By combining mutations, a 10-fold mutant was generated with a Tm of 94 °C (+51 °C relative to wild type), almost reaching water's boiling point, and the highest increase with FRESCO to date. The 10-fold mutant's structure was elucidated, which enabled the identification of an activity-impairing mutation. After reverting this mutation, the enzyme showed no loss in activity compared to wild type, while displaying a Tm of 88 °C (+45 °C relative to wild type). This work demonstrates the value of enzyme stabilization through computational library design.

Periodic Event-Triggered Control strategy for a (3,0) mobile robot network.

This work deals with the development of a nonlinear Periodic Event-Triggered Control strategy employed to the consensus of a multi-vehicle autonomous system based on (3,0) mobile robots. First, the existence of the Control Lyapunov Function (CLF) applicable to the consensus problem is proven. This is subsequently used to develop event and feedback functions. The Periodic Event-Triggered Control ensures trajectories boundedness and convergence to consensus while a specific sampling period is provided. Also, the formation problem is addressed as an extension of the presented work. Experimental results show the performance of the proposed control strategy which reduces 99.78% the number of control updates compared to a continuous control law, resulting in energy saving for the information transfer from central control to the mobile robots.

Leader-Following Consensus and Formation Control of VTOL-UAVs with Event-Triggered Communications †.

This article presents the design and implementation of an event-triggered control approach, applied to the leader-following consensus and formation of a group of autonomous micro-aircraft with capabilities of vertical take-off and landing (VTOL-UAVs). The control strategy is based on an inner-outer loop control approach. The inner control law stabilizes the attitude and position of one agent, whereas the outer control follows a virtual leader to achieve position consensus cooperatively through an event-triggered policy. The communication topology uses undirected and connected graphs. With such an event-triggered control, the closed-loop trajectories converge to a compact sphere, centered in the origin of the error space. Furthermore, the minimal inter-sampling time is proven to be below bounded avoiding the Zeno behavior. The formation problem addresses the group of agents to fly in a given shape configuration. The simulation and experimental results highlight the performance of the proposed control strategy.

Biocatalytic production of bicyclic ß-lactams with three contiguous chiral centres using engineered crotonases.

There is a need to develop asymmetric routes to functionalised ß-lactams, which remain the most important group of antibacterials. Here we describe biocatalytic and protein engineering studies concerning carbapenem biosynthesis enzymes, aiming to enable stereoselective production of functionalised carbapenams with three contiguous chiral centres. Structurally-guided substitutions of wildtype carboxymethylproline synthases enable tuning of their C-N and C-C bond forming capacity to produce 5-carboxymethylproline derivatives substituted at C-4 and C-6, from amino acid aldehyde and malonyl-CoA derivatives. Use of tandem enzyme incubations comprising an engineered carboxymethylproline synthase and an alkylmalonyl-CoA forming enzyme (i.e. malonyl-CoA synthetase or crotonyl-CoA carboxylase reductase) can improve stereocontrol and expand the product range. Some of the prepared 4,6-disubstituted-5-carboxymethylproline derivatives are converted to bicyclic ß-lactams by carbapenam synthetase catalysis. The results illustrate the utility of tandem enzyme systems involving engineered crotonases for asymmetric bicyclic ß-lactam synthesis.

Resin-Dentin Bonding Interface: Mechanisms of Degradation and Strategies for Stabilization of the Hybrid Layer.

Several studies have shown that the dentin-resin interface is unstable due to poor infiltration of resin monomers into the demineralized dentin matrix. This phenomenon is related to the incomplete infiltration of the adhesive system into the network of exposed collagen fibrils, mainly due to the difficulty of displacement and subsequent replacement of trapped water between interfibrillar spaces, avoiding adequate hybridization within the network of collagen fibrils. Thus, unprotected fibrils are exposed to undergo denaturation and are susceptible to cyclic fatigue rupture after being subjected to repetitive loads during function. The aqueous inclusions within the hybrid layer serve as a functional medium for the hydrolysis of the resin matrix, giving rise to the activity of esterases and collagenolytic enzymes, such as matrix metalloproteinases, which play a fundamental role in the degradation process of the hybrid layer. Achieving better interdiffusion of the adhesive system in the network of collagen fibrils and the substrate stability in the hybrid layer through different strategies are key events for the interfacial microstructure to adequately function. Hence, it is important to review the factors related to the mechanisms of degradation and stabilization of the hybrid layer to support the implementation of new materials and techniques in the future. The enzymatic degradation of collagen matrix, together with resin leaching, has led to seeking strategies that inhibit the endogenous proteases, cross-linking the denudated collagen fibrils and improving the adhesive penetration removing water from the interface. Some of dentin treatments have yielded promising results and require more research to be validated. A longer durability of adhesive restorations could resolve a variety of clinical problems, such as microleakage, recurrent caries, postoperative sensitivity, and restoration integrity.

Development of a three-wave far-infrared laser interferometry and polarimetry diagnostic system for the C-2W field-reversed configuration plasmas.

Great advancements in modern field-reversed configuration (FRC) experiments motivated the development of a 14-chord three-wave far infrared (FIR) laser interferometry and polarimetry diagnostic system, which can provide simultaneous high temporal resolution measurements of density and Faraday rotation profiles with high accuracy. The unique challenges facing FIR diagnostics in high beta FRC plasmas are the extremely small (<0.5°) Faraday rotation angles, and severe laser beam refraction effects due to high density gradient and choice of long wavelength. The diagnostic system design and development are described with methods to overcome the challenges, and initial experimental data are also presented.

The crystal structure of P450-TT heme-domain provides the first structural insights into the versatile class VII P450s.

The first crystal structure of a class VII P450, CYP116B46 from Tepidiphilus thermophilus, has been solved at 1.9 Šresolution. The structure reveals overall conservation of the P450-fold and a water conduit around the I-helix. Active site residues have been identified and sequence comparisons have been made with other class VII enzymes. A structure similarity search demonstrated that the P450-TT structure is similar to enzymes capable of oxy-functionalization of fatty acids, terpenes, macrolides, steroids and statins. The insight gained from solving this structure will provide a guideline for future engineering and modelling studies on this catalytically promiscuous class of enzymes.

Same Substrate, Many Reactions: Oxygen Activation in Flavoenzymes.

Over time, organisms have evolved strategies to cope with the abundance of dioxygen on Earth. Oxygen-utilizing enzymes tightly control the reactions involving O2 mostly by modulating the reactivity of their cofactors. Flavins are extremely versatile cofactors that are capable of undergoing redox reactions by accepting either one electron or two electrons, alternating between the oxidized and the reduced states. The physical and chemical principles of flavin-based chemistry have been investigated widely. In the following pages we summarize the state of the art on a key area of research in flavin enzymology: the molecular basis for the activation of O2 by flavin-dependent oxidases and monooxygenases. In general terms, oxidases use O2 as an electron acceptor to produce H2O2, while monooxygenases activate O2 by forming a flavin intermediate and insert an oxygen atom into the substrate. First, we analyze how O2 reaches the flavin cofactor embedded in the protein matrix through dedicated access pathways. Then we approach O2 activation from the perspective of the monooxygenases, their preferred intermediate, the C(4a)-(hydro)peroxyflavin, and the cases in which other intermediates have been described. Finally, we focus on understanding how the architectures developed in the active sites of oxidases promote O2 activation and which other factors operate in its reactivity.