Polar confinement of the Sun's interior magnetic field by laminar magnetostrophic flow

The global-scale interior magnetic field needed to account for the Sun's observed differential rotation can be effective only if confined below the convection zone in all latitudes, including the polar caps. Axisymmetric nonlinear MHD solutions are obtained showing that such confinement can be brought about by a very weak downwelling flow U~10^{-5}cm/s over each pole. Such downwelling is consistent with the helioseismic evidence. All three components of the magnetic field decay exponentially with altitude across a thin "magnetic confinement layer" located at the bottom of the tachocline. With realistic parameter values, the thickness of the confinement layer ~10^{-3} of the Sun's radius. Alongside baroclinic effects and stable thermal stratification, the solutions take into account the stable compositional stratification of the helium settling layer, if present as in today's Sun, and the small diffusivity of helium through hydrogen, chi. The small value of chi relative to magnetic diffusivity produces a double boundary-layer structure in which a "helium sublayer" of smaller vertical scale is sandwiched between the top of the helium settling layer and the rest of the confinement layer. Solutions are obtained using both semi-analytical and purely numerical, finite-difference techniques. The confinement-layer flows are magnetostrophic to excellent approximation. More precisely, the principal force balances are between Lorentz, Coriolis, pressure-gradient and buoyancy forces, with relative accelerations and viscous forces negligible. This is despite the kinematic viscosity being somewhat greater than chi. We discuss how the confinement layers at each pole might fit into a global dynamical picture of the solar tachocline. That picture, in turn, suggests a new insight into the early Sun and into the longstanding enigma of solar lithium depletion.Comment: Accepted by JFM. 36 pages, 10 figure

A general theorem on angular-momentum changes due to potential vorticity mixing and on potential-energy changes due to buoyancy mixing

An initial zonally symmetric quasigeostrophic potential-vorticity (PV) distribution q_i(y) is subjected to complete or partial mixing within some finite zone |y| < L, where y is latitude. The change in M, the total absolute angular momentum, between the initial and any later time is considered. For standard quasigeostrophic shallow-water beta-channel dynamics it is proved that, for any q_i(y) such that dq_i/dy > 0 throughout |y| < L, the change in M is always negative. This theorem holds even when "mixing" is understood in the most general possible sense. Arbitrary stirring or advective rearrangement is included, combined to an arbitrary extent with spatially inhomogeneous diffusion. The theorem holds whether or not the PV distribution is zonally symmetric at the later time. The same theorem governs Boussinesq potential-energy changes due to buoyancy mixing in the vertical. For the standard quasigeostrophic beta-channel dynamics to be valid the Rossby deformation length L_D >> \epsilon L where \epsilon is the Rossby number; when L_D = \infty the theorem applies not only to the beta-channel, but also to a single barotropic layer on the full sphere, as considered in the recent work of Dunkerton and Scott on "PV staircases". It follows that the M-conserving PV reconfigurations studied by those authors must involve processes describable as PV unmixing, or anti-diffusion, in the sense of time-reversed diffusion. Ordinary jet self-sharpening and jet-core acceleration do not, by contrast, require unmixing, as is shown here by detailed analysis. Mixing in the jet flanks suffices. The theorem extends to multiple layers and continuous stratification. A corollary is a new nonlinear stability theorem for shear flows.Comment: 14 pages, 4 figures; Final version, accepted by J. Atmos. Sci, in pres

Implementing an application programming interface for PROMIS measures at three medical centers

BACKGROUND: There is an increasing body of literature advocating for the collection of patient-reported outcomes (PROs) in clinical care. Unfortunately, there are many barriers to integrating PRO measures, particularly computer adaptive tests (CATs), within electronic health records (EHRs), thereby limiting access to advances in PRO measures in clinical care settings. OBJECTIVE: To address this obstacle, we created and evaluated a software integration of an Application Programming Interface (API) service for administering and scoring Patient-Reported Outcomes Measurement Information System (PROMIS) measures with the EHR system. METHODS: We created a RESTful API and evaluated the technical feasibility and impact on clinical workflow at three academic medical centers. RESULTS: Collaborative teams (i.e., clinical, information technology [IT] and administrative staff) performed these integration efforts addressing issues such as software integration as well as impact on clinical workflow. All centers considered their implementation successful based on the high rate of completed PROMIS assessments (between January 2016 and January 2021) and minimal workflow disruptions. CONCLUSION: These case studies demonstrate not only the feasibility but also the pathway for the integration of PROMIS CATs into the EHR and routine clinical care. All sites utilized diverse teams with support and commitment from institutional leadership, initial implementation in a single clinic, a process for monitoring and optimization, and use of custom software to minimize staff burden and error

Isolating the photovoltaic junction: atomic layer deposited TiO2-RuO2 alloy Schottky contacts for silicon photoanodes

We synthesized nanoscale TiO2-RuO2 alloys by atomic layer deposition (ALD) that possess a high work function and are highly conductive. As such, they function as good Schottky contacts to extract photogenerated holes from n-type silicon while simultaneously interfacing with water oxidation catalysts. The ratio of TiO2 to RuO2 can be precisely controlled by the number of ALD cycles for each precursor. Increasing the composition above 16% Ru sets the electronic conductivity and the metal work function. No significant Ohmic loss for hole transport is measured as film thickness increases from 3 to 45 nm for alloy compositions >= 16% Ru. Silicon photoanodes with a 2 nm SiO2 layer that are coated by these alloy Schottky contacts having compositions in the range of 13-46% Ru exhibit average photovoltages of 525 mV, with a maximum photovoltage of 570 mV achieved. Depositing TiO2-RuO2 alloys on nSi sets a high effective work function for the Schottky junction with the semiconductor substrate, thus generating a large photovoltage that is isolated from the properties of an overlying oxygen evolution catalyst or protection layer

Quantitative diffusion tensor imaging detects dopaminergic neuronal degeneration in a murine model of Parkinson\u27s disease.

Early diagnosis of Parkinson\u27s disease (PD) is required to improve therapeutic responses. Indeed, a clinical diagnosis of resting tremor, rigidity, movement and postural deficiencies usually reflect \u3e50% loss of the nigrostriatal system in disease. In a step to address this, quantitative diffusion tensor magnetic resonance imaging (DTI) was used to assess nigrostriatal degeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication model of dopaminergic nigral degeneration. We now demonstrate increased average diffusion (p\u3c0.005) and decreased fractional anisotropy (p\u3c0.03) in the substantia nigra (SN) of 5- to 7-day MPTP-treated animals when compared to saline controls. Transverse diffusivity demonstrated the most significant differences (p \u3c or = 0.002) and correlated with the numbers of SN dopaminergic neurons (r=-0.75, p=0.012). No differences were found in the striatum, corpus callosum, cerebral cortex, or ventricles. These results demonstrate that DTI may be used as a surrogate biomarker of nigral dopaminergic neuronal degeneration

The Cutaneous Microbiome and Wounds: New Molecular Targets to Promote Wound Healing

The ecological community of microorganisms in/on humans, termed the microbiome, is vital for sustaining homeostasis. While culture-independent techniques have revealed the role of the gut microbiome in human health and disease, the role of the cutaneous microbiome in wound healing is less defined. Skin commensals are essential in the maintenance of the epithelial barrier function, regulation of the host immune system, and protection from invading pathogenic microorganisms. In this review, we summarize the literature derived from pre-clinical and clinical studies on how changes in the microbiome of various acute and chronic skin wounds impact wound healing tissue regeneration. Furthermore, we review the mechanistic insights garnered from model wound healing systems. Finally, in the face of growing concern about antibiotic-resistance, we will discuss alternative strategies for the treatment of infected wounds to improve wound healing and outcomes. Taken together, it has become apparent that commensals, symbionts, and pathogens on human skin have an intimate role in the inflammatory response that highlights several potential strategies to treat infected, non-healing wounds. Despite these promising results, there are some contradictory and controversial findings from existing studies and more research is needed to define the role of the human skin microbiome in acute and chronic wound healing

Accurate H-atom parameters for the two polymorphs of L-histidine at 5, 105 and 295 K

The crystal structure of the monoclinic polymorph of the primary amino acid l-histidine has been determined for the first time by single-crystal neutron diffraction, while that of the orthorhombic polymorph has been reinvestigated with an untwinned crystal, improving the experimental precision and accuracy. For each polymorph, neutron diffraction data were collected at 5, 105 and 295 K. Single-crystal X-ray diffraction experiments were also performed at the same temperatures. The two polymorphs, whose crystal packing is interpreted by intermolecular interaction energies calculated using the Pixel method, show differences in the energy and geometry of the hydrogen bond formed along the c direction. Taking advantage of the X-ray diffraction data collected at 5 K, the precision and accuracy of the new Hirshfeld atom refinement method implemented in NoSpherA2 were probed choosing various settings of the functionals and basis sets, together with the use of explicit clusters of molecules and enhanced rigid-body restraints for H atoms. Equivalent atomic coordinates and anisotropic displacement parameters were compared and found to agree well with those obtained from the corresponding neutron structural models

Acoustic Energy and Momentum in a Moving Medium

By exploiting the mathematical analogy between the propagation of sound in a non-homogeneous potential flow and the propagation of a scalar field in a background gravitational field, various wave ``energy'' and wave ``momentum'' conservation laws are established in a systematic manner. In particular the acoustic energy conservation law due to Blokhintsev appears as the result of the conservation of a mixed co- and contravariant energy-momentum tensor, while the exchange of relative energy between the wave and the mean flow mediated by the radiation stress tensor, first noted by Longuet-Higgins and Stewart in the context of ocean waves, appears as the covariant conservation of the doubly contravariant form of the same energy-momentum tensor.Comment: 25 Pages, Late

Ultra-low temperature structure determination of a Mn12 single-molecule magnet and the interplay between lattice solvent and structural disorder

We have determined the ultra-low temperature crystal structure of the archetypal single-molecule magnet (SMM) [Mn12O12(O2CMe)16(H2O)4]·4H2O·2MeCO2H (1) at 2 K, by using a combination of single-crystal X-ray and single-crystal neutron diffraction. This is the first structural study of any SMM in the same temperature regime where slow magnetic relaxation occurs. We reveal an additional hydrogen bonding interaction between the {Mn12} cluster and its solvent of crystallisation, which shows how the lattice solvent transmits disorder to the acetate ligands in the {Mn12} complex. Unusual quantum properties observed in 1 have long been attributed to disorder. Hence, we studied the desolvation products of 1, in order to understand precisely the influence of lattice solvent on the structure of the cluster. We present two new axially symmetric structures corresponding to different levels of desolvation of 1, [Mn12O12(O2CMe)16(H2O)4]·4H2O (2) and [Mn12O12(O2CMe)16(H2O)4] (3). In 2, removal of acetic acid of crystallisation largely resolves positional disorder in the affected acetate ligands, whereas removal of lattice water molecules further resolves the acetate ligand disorder in 3. Due to the absence of acetic acid of crystallisation, both 2 and 3 have true, unbroken S4 symmetry, showing for the first time that it is possible to prepare fully axial Mn12–acetate analogues from 1, via single-crystal to single-crystal transformations