1,214 research outputs found
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
Postoperative air leak grading is useful to predict prolonged air leak after pulmonary lobectomy
Local structural studies of BaKFeAs using atomic pair distribution function analysis
Systematic local structural studies of BaKFeAs system are
undertaken at room temperature using atomic pair distribution function (PDF)
analysis. The local structure of the BaKFeAs 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
( = ). The crystal unit cell parameters, the
FeAs 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 BaKFeAs
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
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
Supersymmetry and Integrability in Planar Mechanical Systems
We present an N=2-supersymmetric mechanical system whose bosonic sector, with
two degrees of freedom, stems from the reduction of an SU(2) Yang-Mills theory
with the assumption of spatially homogeneous field configurations and a
particular ansatz imposed on the gauge potentials in the dimensional reduction
procedure. The Painleve test is adopted to discuss integrability and we focus
on the role of supersymmetry and parity invariance in two space dimensions for
the attainment of integrable or chaotic models. Our conclusion is that the
relationships among the parameters imposed by supersymmetry seem to drastically
reduce the number of possibilities for integrable interaction potentials of the
mechanical system under consideration.Comment: 20 pages, 3 figure
Angiotensi-converting enzyme DD genotype, angiotensin type 1 receptor CC genotype, and hyperhomocysteinmeia increase first-trimester fetal-loss susceptibility
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