A DC-DC Step-Up mu-Power Converter for Energy Harvesting Applications, Using Maximum Power PointTracking, Based on Fractional Open Circuit Voltage

A DC-DC step-up micro power converter for solar energy harvesting applications is presented. The circuit is based on a switched-capacitorvoltage tripler architecture with MOSFET capacitors, which results in an, area approximately eight times smaller than using MiM capacitors for the 0.131mu m CMOS technology. In order to compensate for the loss of efficiency, due to the larger parasitic capacitances, a charge reutilization scheme is employed. The circuit is self-clocked, using a phase controller designed specifically to work with an amorphous silicon solar cell, in order to obtain themaximum available power from the cell. This will be done by tracking its maximum power point (MPPT) using the fractional open circuit voltage method. Electrical simulations of the circuit, together with an equivalent electrical model of an amorphous silicon solar cell, show that the circuit can deliver apower of 1132 mu W to the load, corresponding to a maximum efficiency of 66.81%

On the Nonlocal Equations and Nonlocal Charges Associated with the Harry Dym Hierarchy

A large class of nonlocal equations and nonlocal charges for the Harry Dym hierarchy is exhibited. They are obtained from nonlocal Casimirs associated with its bi-Hamiltonian structure. The Lax representation for some of these equations is also given.Comment: to appear in Journal of Mathematical Physics, 17 pages, Late

Fluid-assisted grain size reduction leads to strain localization in oceanic transform faults

Oceanic Transform Faults are major plate boundaries representing the most seismogenic part of the mid ocean ridge system. Nonetheless, their structure and deformation mechanisms at depth are largely unknown due to rare exposures of deep sections. Here we study the mineral fabric of deformed mantle peridotites - ultramafic mylonites - collected from the transpressive Atobá ridge, along the northern fault of the St. Paul transform system in the Equatorial Atlantic Ocean. We show that, at pressure and temperature conditions of the lower oceanic lithosphere, the dominant deformation mechanism is fluid-assisted dissolution-precipitation creep. Grain size reduction during deformation is enhanced by dissolution of coarser pyroxene grains in presence of fluid and contextual precipitation of small interstitial ones, leading to strain localization at lower stresses than dislocation creep. This mechanism potentially represents the dominant weakening factor in the oceanic lithosphere and a main driver for the onset and maintenance of oceanic transform faults

Local structural studies of Ba1−x_{1-x}Kx_xFe2_2As2_2 using atomic pair distribution function analysis

Systematic local structural studies of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ system are undertaken at room temperature using atomic pair distribution function (PDF) analysis. The local structure of the Ba$_{1-x}$K$_x$Fe$_2$As$_2$ is found to be well described by the long-range structure extracted from the diffraction experiments, but with anisotropic atomic vibrations of the constituent atoms ($U_{11}$ = $U_{22} \ne U_{33}$). The crystal unit cell parameters, the FeAs$_4$ tetrahedral angle and the pnictogen height above the Fe-plane are seen to show systematic evolution with K doping, underlining the importance of the structural changes, in addition to the charge doping, in determining the properties of Ba$_{1-x}$K$_x$Fe$_2$As$_2$

A new dedicated clinic for HCWs' counseling and vaccination: experience of an academic hospital

Abstract Issue Despite low healthcare workers (HCWs) vaccination coverage being a risk for hospital outbreaks, vaccine hesitancy is not unusual among HCWs. In Italy vaccinations are strongly recommended for HCWs, but there are few occasions for a dedicated counseling. Aim of the study is to evaluate the effectiveness of a new vaccination service in the academic hospital of Udine (northern Italy) in tackling vaccine hesitancy among HCWs. Description of the problem Available data on HCWs specific antibody titers revealed that in high-risk units, 25% of HCWs were certainly unprotected for at least 1/6 of the vaccine preventable diseases (VPDs): measles, rubella, mumps, varicella, pertussis, hepatitis B; only varicella coverage reached the herd immunity target. Periodic occupational health visit was the only moment to screen for VPDs protection and suggest vaccination, but the following inconvenient procedure of HCWs contacting the vaccination office outside the hospital, often lead to delays or loss. In order to improve vaccination adherence, since June 2019 a dedicated clinic has been set up inside the hospital, making vaccination counseling and administration available every two weeks, with appointments directly given by the occupational doctor. Results From June 2019 to February 2020, a total of 362 appointments were booked for the dedicated vaccination clinic, 69.7% of which actually took place as 252 HCWs actually accessed the service. Hours dedicated to the service activity were 76 hours, distributed over 19 days. Administered vaccination were 322, including 107 MMR (measles, rubella, mumps), 4 MMRV (MMR+varicella), 20 varicella, 64 hepatitis B, 127 DTPa (diphtheria, tetanus, pertussis). Lessons Making the access to vaccination more convenient in term of service location within the hospital and giving the appointment when performing the occupational health visit seems to be helpful in filling the VPDs protection among HCWs gap. Key messages Monitoring immunological status of HCWs and promoting vaccination at occupational health visit would sustain herd immunity protection for susceptible individuals in healthcare settings. The dedicated hospital vaccination clinic and the effective procedure of giving the appointment during the occupational health visit could be helpful in improving HCWs vaccine adherence

Crystal structure and phase transitions across the metal-superconductor boundary in the SmFeAsO1-xFx (0 < x < 0.20) family

The fluorine-doped rare-earth iron oxyarsenides, REFeAsO1-xFx (RE =rare earth) have recently emerged as a new family of high-temperature superconductors with transition temperatures (Tc) as high as 55 K (refs 1-4). Early work has provided compelling evidence that the undoped parent materials exhibit spin-density-wave (SDW) antiferromagnetic order and undergo a structural phase transition from tetragonal to orthorhombic crystal symmetry upon cooling.5 Both the magnetic and structural instabilities are suppressed upon doping with fluoride ions before the appearance of superconductivity.6,7 Here we use high-resolution synchrotron X-ray diffraction to study the structural properties of SmFeAsO1-xFx (0 < x < 0.20) in which superconductivity emerges near x ~ 0.07 and Tc increases monotonically with doping up to x ~ 0.20.8 We find that orthorhombic symmetry survives through the metal-superconductor boundary well into the superconducting regime 2 and the structural distortion is only suppressed at doping levels, x > 0.15 when the superconducting phase becomes metrically tetragonal. Remarkably this crystal symmetry crossover coincides with reported drastic anomalies in the resistivity and the Hall coefficient8 and a switch of the pressure coefficient of Tc from positive to negative,9 thereby implying that the low-temperature structure plays a key role in defining the electronic properties of these superconductors

Mineral carbonation of peridotite fueled by magmatic degassing and melt impregnation in an oceanic transform fault

Most of the geologic CO2 entering Earth's atmosphere and oceans is emitted along plate margins. While C-cycling at mid-ocean ridges and subduction zones has been studied for decades, little attention has been paid to degassing of magmatic CO2 and mineral carbonation of mantle rocks in oceanic transform faults. We studied the formation of soapstone (magnesite-talc rock) and other magnesite-bearing assemblages during mineral carbonation of mantle peridotite in the St. Paul's transform fault, equatorial Atlantic. Clumped carbonate thermometry of soapstone yields a formation (or equilibration) temperature of 147 ± 13 °C which, based on thermodynamic constraints, suggests that CO2(aq) concentrations of the hydrothermal fluid were at least an order of magnitude higher than in seawater. The association of magnesite with apatite in veins, magnesite with a δ13C of -3.40 ± 0.04‰, and the enrichment of CO2 in hydrothermal fluids point to magmatic degassing and melt-impregnation as the main source of CO2. Melt-rock interaction related to gas-rich alkali olivine basalt volcanism near the St. Paul's Rocks archipelago is manifested in systematic changes in peridotite compositions, notably a strong enrichment in incompatible elements with decreasing MgO/SiO2. These findings reveal a previously undocumented aspect of the geologic carbon cycle in one of the largest oceanic transform faults: Fueled by magmatism in or below the root zone of the transform fault and subsequent degassing, the fault constitutes a conduit for CO2-rich hydrothermal fluids, while carbonation of peridotite represents a vast sink for the emitted CO2

Residual Kidney Function Decline and Mortality in Incident Hemodialysis Patients.

In patients with ESRD, residual kidney function (RKF) contributes to achievement of adequate solute clearance. However, few studies have examined RKF in patients on hemodialysis. In a longitudinal cohort of 6538 patients who started maintenance hemodialysis over a 4-year period (January 2007 through December 2010) and had available renal urea clearance (CLurea) data at baseline and 1 year after hemodialysis initiation, we examined the association of annual change in renal CLurea rate with subsequent survival. The median (interquartile range) baseline value and mean±SD annual change of CLurea were 3.3 (1.9-5.0) and -1.1±2.8 ml/min per 1.73 m2, respectively. Greater CLurea rate 1 year after hemodialysis initiation associated with better survival. Furthermore, we found a gradient association between loss of RKF and all-cause mortality: changes in CLurea rate of -6.0 and +3.0 ml/min per 1.73 m2 per year associated with case mix-adjusted hazard ratios (95% confidence intervals) of 2.00 (1.55 to 2.59) and 0. 61 (0.50 to 0.74), respectively (reference: -1.5 ml/min per 1.73 m2 per year). These associations remained robust against adjustment for laboratory variables and ultrafiltration rate and were consistent across strata of baseline CLurea, age, sex, race, diabetes status, presence of congestive heart failure, and hemoglobin, serum albumin, and serum phosphorus levels. Sensitivity analyses using urine volume as another index of RKF yielded consistent associations. In conclusion, RKF decline during the first year of dialysis has a graded association with all-cause mortality among incident hemodialysis patients. The clinical benefits of RKF preservation strategies on mortality should be determined