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The aim of this study was to describe oral lesions in a group of patients with COVID-19. We recruited 55 patients, 25 women (45.5%) and 30 men (54.5%), aged between 1 and 89 years with confirmed COVID-19 at different stages of severity. After obtaining informed consent, we examined their mouths and recorded clinical findings. Forty percent of the patients had at least 1 oral lesion. The most common lesions were candidiasis and ulcers (7 patients each); 2 patients had enanthems. Geographic tongue and caviar tongue were also observed. Altered taste, dry mouth, and painful/burning mouth were noted in 60%, 27.3%, and 36.4% of patients, respectively. Oral mucosal alterations and lesions were prevalent in this series of COVID-19 patients. Altered taste and a painful/burning mouth were common symptoms.

La pérdida de masa ósea, como consecuencia del remodelado óseo, en el tercio proximal del fémur, es un factor que contribuye al fracaso de las prótesis de cadera a medio-largo plazo. Este remodelado periprotésico se desarrolla sobre todo durante los 12 primeros meses tras la intervención.

Nitrate legacy is affecting groundwater sources across the tropics. This study describes isotopic and ionic spatial trends across a tropical, fractured, volcanic multi‐aquifer system in central Costa Rica in relation to land use change over four decades. Springs and wells (from 800 to 2,400 m asl) were sampled for NO3−and Cl−concentrations, δ18Owater, δ15NNO3, and δ18ONO3. A Bayesian isotope mixing model was used to estimate potential source contributions to the nitrate legacy in groundwater. Land use change was evaluated using satellite imagery from 1979 to 2019. The lower nitrate concentrations (<1 mg/L NO3−N) were reported in headwater springs near protected forested areas, while greater concentrations (up to ∼63 mg/L) were reported in wells (mid‐ and low‐elevation sites in the unconfined unit) and low‐elevation springs. High‐elevation springs were characterized by low Cl−and moderate NO3−/Cl−ratios, indicating the potential influence of soil nitrogen (SN) inputs. Wells and low‐elevation springs exhibited greater NO3−/Cl−ratios and Cl−concentrations above 100 μmol/L. Bayesian calculations suggest a mixture of sewage (domestic septic tanks), SN (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. Our results confirm the incipient trend in increasing groundwater nitrogen and highlight the urgent need for a multi‐municipal plan to transition from domestic septic tanks to regional sewage treatment and sustainable agricultural practices to prevent future groundwater quality degradation effectively. This study analyzed different nitrate sources in a complex tropical groundwater system and how they were affected by changes in land use over the last decades. In general, high‐elevation areas near protected forests are represented by lower nitrate levels, while mid‐ and low‐elevations areas exhibited greater nitrate and chloride concentrations. Our results suggest that groundwater nitrate reflects a legacy mixture of sewage (domestic septic tanks), soil nitrogen (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. The identified nitrate groundwater legacy in the Central Valley of Costa Rica, evidenced by unprecedented decadal nitrate isotope data, could serve as a valid example of the potential impact of abrupt urbanization growth across the wet tropics. Four decades of land use change have increased groundwater nitrate concentrations in central Costa RicaDeeper aquifer units were characterized by low nitrate concentrations, whereas greater values were reported in the shallow unconfined unitNitrogen and oxygen stable isotopes revealed unknown recharge mechanisms and nitrogen pollution sources in a tropical volcanic aquifer Four decades of land use change have increased groundwater nitrate concentrations in central Costa Rica Deeper aquifer units were characterized by low nitrate concentrations, whereas greater values were reported in the shallow unconfined unit Nitrogen and oxygen stable isotopes revealed unknown recharge mechanisms and nitrogen pollution sources in a tropical volcanic aquifer

For decades, the Vlasov–Darwin model has been recognized to be attractive for particle-in-cell (PIC) kinetic plasma simulations in non-radiative electromagnetic regimes, to avoid radiative noise issues and gain computational efficiency. However, the Darwin model results in an elliptic set of field equations that renders conventional explicit time integration unconditionally unstable. Here, we explore a fully implicit PIC algorithm for the Vlasov–Darwin model in multiple dimensions, which overcomes many difficulties of traditional semi-implicit Darwin PIC algorithms. The finite-difference scheme for Darwin field equations and particle equations of motion is space–time-centered, employing particle sub-cycling and orbit-averaging. The algorithm conserves total energy, local charge, canonical-momentum in the ignorable direction, and preserves the Coulomb gauge exactly. An asymptotically well-posed fluid preconditioner allows efficient use of large cell sizes, which are determined by accuracy considerations, not stability, and can be orders of magnitude larger than required in a standard explicit electromagnetic PIC simulation. We demonstrate the accuracy and efficiency properties of the algorithm with various numerical experiments in 2D–3V. [ABSTRACT FROM AUTHOR]

A recent proof-of-principle study proposes a nonlinear electrostatic implicit particle-in-cell (PIC) algorithm in one dimension (Chen et al., 2011). The algorithm employs a kinetically enslaved Jacobian-free Newton-Krylov (JFNK) method, and conserves energy and charge to numerical round-off. In this study, we generalize the method to electromagnetic simulations in 1D using the Darwin approximation to Maxwell's equations, which avoids radiative noise issues by ordering out the light wave. An implicit, orbit-averaged, time-space-centered finite difference scheme is employed in both the 1D Darwin field equations (in potential form) and the 1D-3V particle orbit equations to produce a discrete system that remains exactly charge- and energy-conserving. Furthermore, enabled by the implicit Darwin equations, exact conservation of the canonical momentum per particle in any ignorable direction is enforced via a suitable scattering rule for the magnetic field. We have developed a simple preconditioner that targets electrostatic waves and skin currents, and allows us to employ time steps O(mi/mec/veT) larger than the explicit CFL. Several 1D numerical experiments demonstrate the accuracy, performance, and conservation properties of the algorithm. In particular, the scheme is shown to be second-order accurate, and CPU speedups of more than three orders of magnitude vs. an explicit Vlasov-Maxwell solver are demonstrated in the "cold" plasma regime (where kλD≪1). [ABSTRACT FROM AUTHOR]

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In the development of spatial difference schemes for magnetohydrodynamics (MHD), the preservation of continuum properties such as conservation of mass, momentum, and energy, as well as required electromagnetic constraints (, where is the electrical current), is desirable to preserve numerical accuracy. Moreover, simplicity of the scheme is also a desirable feature, particularly when an implicit implementation is considered (the focus of this paper). We propose here a finite-volume, cell-centered (non-staggered) scheme for the extended MHD formulation that: (1) is suitable for implicit implementations in arbitrary curvilinear geometries, (2) is conservative, (3) preserves both the magnetic field and the electrical current solenoidal to machine precision, and (4) is linearly and nonlinearly stable in the absence of numerical and physical dissipation. Crucial to the viability of the scheme is the use of a clever interpolation scheme (ZIP [Hirt, J. Comput. Phys. 2 (1968) 339–355]), the proper treatment of boundary conditions in curvilinear geometry, and a novel treatment of geometric source terms in the momentum equation that ensures their exact cancellation in the absence of pressure forces. [Copyright &y& Elsevier]

Energy-conservative implicit integration schemes for the Fokker–Planck transport equation in multidimensional geometries require inverting a dense, non-symmetric matrix (Jacobian), which is very expensive to store and solve using standard solvers. However, these limitations can be overcome with Newton–Krylov iterative techniques, since they can be implemented Jacobian-free(the Jacobian matrix from Newton's algorithm is never formed nor stored to proceed with the iteration), and their convergence can be accelerated by preconditioningthe original problem. In this document, the efficient numerical implementation of an implicit energy-conservative scheme for multidimensional Fokker–Planck problems using multigrid-preconditioned Krylov methods is discussed. Results show that multigrid preconditioning is very effective in speeding convergence and decreasing CPU requirements, particularly in fine meshes. The solver is demonstrated on grids up to 128×128 points in a 2D cylindrical velocity space (vr, vp) with implicit time steps of the order of the collisional time scale of the problem, τ. The method preserves particles exactly, and energy conservation is improved over alternative approaches, particularly in coarse meshes. Typical errors in the total energy over a time period of 10τ remain below a percent.

Ipomoea stans(IS) has long been used as an anticonvulsant. Although the use of HPLC and nuclear magnetic resonance techniques recently have allowed some of its compounds to be identified, the anticonvulsant properties of this Convolvulaceae remained to be tested. During the course of several weeks, mice (BALB/C) were given a normal infusion of the plant instead of clean water (IS-ad lib). They also were given total lyophilized powder (IS-T), and two mixtures of compounds (IS-A and IS-B) from the plant. Their convulsive thresholds were then tested with pentylenetetrazol (PTZ: 40, 60, 85 and 100mg/kg, s.c.) and electric shock (ECS: 0.1mAmp, 60 Hz). Results showed Ipomoea stansprovides protection against ECS and a low dose of PTZ (40 mg/kg). However, some data from animals who died following ECS after receiving a high regimen of IS suggests they suffered mesenteric infarct. Similar results appeared after treatments with IS-T and IS-A. All IS preparations offered protection but IS-B in particular protected mice against seizures produced by a low dose of PTZ (40 mg/kg) and delayed the onset of seizures produced by ECS. In a second set of experiments, IS-ad liband IS-T increased the threshold for amygdala discharges produced by the cortical electrical stimulation in Wistar rats. It is concluded that IS possesses some anticonvulsant properties similar to valproic acid, that are attributable to fraction B of the plant. Fraction A seems to possess a weaker anticonvulsant activity and some toxic properties.

Finite-grid (or aliasing) instabilities are pervasive in particle-in-cell (PIC) plasma simulation algorithms, and force the modeler to resolve the smallest (Debye) length scale in the problem regardless of dynamical relevance. These instabilities originate in the aliasing of interpolation errors between mesh quantities and particles (which live in the space–time continuum). Recently, strictly energy-conserving PIC (EC-PIC) algorithms have been developed that promise enhanced robustness against aliasing instabilities. In this study, we confirm by analysis that EC-PIC is stable against aliasing instabilities for stationary plasmas. For drifting plasmas, we demonstrate by analysis and numerical experiments that, while EC-PIC algorithms are not free from these instabilities in principle, they feature a benign stability threshold for finite-temperature plasmas that make them usable in practice for a large class of problems (featuring ambipolarity and realistic ion-electron mass ratios) without the need to consider the size of the Debye length. We also demonstrate that this threshold is absent for the popular momentum-conserving PIC algorithms, which are therefore unstable for both drifting and stationary plasmas beyond a threshold in cell size compared to Debye length. [ABSTRACT FROM AUTHOR]

We develop a conservative configuration- and velocity-space (i.e., phase-space) moving-grid strategy for the Vlasov–Fokker–Planck (VFP) equation in a planar geometry. The velocity-space grid is normalized and shifted in terms of the thermal speed and the bulk-fluid velocity, respectively. The configuration-space grid is moved according to a mesh-motion-partial-differential equation (MMPDE), which equidistributes a monitor function that is inversely proportional to the gradient-length scales of the macroscopic plasma quantities. The resulting inertial terms in the transformed VFP equations are discretized to ensure the discrete conservation of mass, momentum, and energy. To satisfy the discrete conservation theorems in the presence of phase-space mesh motion, we employ the method of discrete nonlinear constraints – explored in previous studies – but the underlying symmetries are determined in a much more efficient manner than before. The conservative grid-adaptivity strategy provides an efficient scheme that resolves important physical structures in the phase-space while controlling the computational complexity at all times. We demonstrate the favorable features of the proposed algorithm through a set of test cases of increasing complexity. The problems test independent components of the algorithms, as well as the integrated capability on settings relevant to inertial confinement fusion. • A conservative and adaptive scheme for the Vlasov–Fokker–Planck (VFP) eqn. in 1D2V is proposed. • Velocity space grid is adapted with a characteristic speed and bulk flow velocity. • In configuration space, we adapt the grid based on an MMPDE scheme. • Adaptivity is achieved while ensuring conservation properties. [ABSTRACT FROM AUTHOR]

The aim of this study was to describe oral lesions in a group of patients with COVID-19. We recruited 55 patients, 25 women (45.5%) and 30 men (54.5%), aged between 1 and 89 years with confirmed COVID-19 at different stages of severity. After obtaining informed consent, we examined their mouths and recorded clinical findings. Forty percent of the patients had at least 1 oral lesion. The most common lesions were candidiasis and ulcers (7 patients each); 2 patients had enanthems. Geographic tongue and caviar tongue were also observed. Altered taste, dry mouth, and painful/burning mouth were noted in 60%, 27.3%, and 36.4% of patients, respectively. Oral mucosal alterations and lesions were prevalent in this series of COVID-19 patients. Altered taste and a painful/burning mouth were common symptoms.

We present a numerical algorithm that enables a phase-space adaptive Eulerian Vlasov–Fokker–Planck (VFP) simulation of inertial confinement fusion (ICF) capsule implosions. The approach relies on extending a recent mass, momentum, and energy conserving phase-space moving-mesh adaptivity strategy to spherical geometry. In configuration space, we employ a mesh motion partial differential equation (MMPDE) strategy while, in velocity space, the mesh is expanded/contracted and shifted with the plasma's evolving temperature and drift velocity. The mesh motion is dealt with by transforming the underlying VFP equations into a computational (logical) coordinate, with the resulting inertial terms carefully discretized to ensure conservation. To deal with the spatial and temporally varying dynamics in a spherically imploding system, we have developed a novel nonlinear stabilization strategy for MMPDE in the configuration space. The strategy relies on a nonlinear optimization procedure that optimizes between mesh quality and the volumetric rate change of the mesh to ensure both accuracy and stability of the solution. Implosions of ICF capsules are driven by several boundary conditions: (1) an elastic moving wall boundary; (2) a time-dependent Maxwellian Dirichlet boundary; and (3) a pressure-driven Lagrangian boundary. Of these, the pressure-driven Lagrangian boundary driver is new to our knowledge. The implementation of our strategy is verified through a set of test problems, including the Guderley and Van-Dyke implosion problems — the first-ever reported using a Vlasov–Fokker–Planck model. • A conservative moving grid for Vlasov–Fokker–Planck (VFP) in spherical geometry is developed. • Nonlinear stabilization strategy for the MMPDE scheme is developed. • Noble boundary conditions to mimic ICF capsule implosion is developed. • First ever reported verification of Guderley and Van-Dyke problem with VFP. • Real Omega capsule implosion is simulated with integrated algorithm. [ABSTRACT FROM AUTHOR]