161 research outputs found
Andreev-Lifshitz supersolid revisited for a few electrons on a square lattice II
In this second paper, using N=3 polarized electrons (spinless fermions)
interacting via a U/r Coulomb repulsion on a two dimensional L * L square
lattice with periodic boundary conditions and nearest neighbor hopping, we show
that a single unpaired fermion can co-exist with a correlated two particle
Wigner molecule for intermediate values of the Coulomb energy to kinetic energy
ratio r_s.Comment: 15 pages, 28 postscript figure
Measuring and simulating magnetic characteristics using epstein frame
The paper discusses the standard of the Epstein frame that has been used to measure magnetic characteristics of the core made of material M250-35A supplied by different frequencies between 1-400 Hz. The measuring program has been built in LabVIEW including a control, filter and data save section as well. COMSOL Multiphysics 4.3b has been chosen as simulation environment, in which the Jiles-Atherton hysteresis model has been implemented
Wintertime hygroscopicity and volatility of ambient urban aerosol particles
Hygroscopic and volatile properties of atmospheric aerosol particles with dry diameters of (20), 50, 75, 110 and 145 nm were determined in situ by using a volatility-hygroscopicity tandem differential mobility analyser (VH-TDMA) system with a relative humidity of 90% and denuding temperature of 270 degrees C in central Budapest during 2 months in winter 2014-2015. The probability density function of the hygroscopic growth factor (HGF) showed a distinct bimodal distribution. One of the modes was characterised by an overall mean HGF of approximately 1.07 (this corresponds to a hygroscopicity parameter kappa of 0.033) independently of the particle size and was assigned to nearly hydrophobic (NH) particles. Its mean particle number fraction was large, and it decreased monotonically from 69 to 41% with particle diameter. The other mode showed a mean HGF increasing slightly from 1.31 to 1.38 (kappa values from 0.186 to 0.196) with particle diameter, and it was attributed to less hygroscopic (LH) particles. The mode with more hygroscopic particles was not identified. The probability density function of the volatility GF (VGF) also exhibited a distinct bimodal distribution with an overall mean VGF of approximately 0.96 independently of the particle size, and with another mean VGF increasing from 0.49 to 0.55 with particle diameter. The two modes were associated with less volatile (LV) and volatile (V) particles. The mean particle number fraction for the LV mode decreased from 34 to 21% with particle diameter. The bimodal distributions indicated that the urban atmospheric aerosol contained an external mixture of particles with a diverse chemical composition. Particles corresponding to the NH and LV modes were assigned mainly to freshly emitted combustion particles, more specifically to vehicle emissions consisting of large mass fractions of soot likely coated with or containing some water-insoluble organic compounds such as non-hygroscopic hydrocarbon-like organics. The hygroscopic particles were ordinarily volatile. They could be composed of moderately transformed aged combustion particles consisting of partly oxygenated organics, inorganic salts and soot. The larger particles contained internally mixed non-volatile chemical species as a refractory residual in 20-25% of the aerosol material (by volume).Peer reviewe
Cost-Utility Analysis of Heberprot-P as an Add-on Therapy to Good Wound Care for Patients in Slovakia with Advanced Diabetic Foot Ulcer
Objectives: To explore whether Heberprot-P (an epidermal growth factor) is a cost-effective option for the treatment of advanced diabetic foot ulcer as an add-on therapy to good wound care (GWC) in Slovakia from the perspective of health care payers. Methods: A Markov model was constructed to compare the costs and effects of Heberprot-P plus GWC to those of GWC alone from the perspective of health care payers. The 52-week clinical trial period was extended to five- and 10-year time horizons. Transition probabilities were calculated based on a previous clinical trial of Heberprot, utility values were derived from the scientific literature, and cost vectors were collected from the General Health Insurance Fund database in Slovakia. A one-way deterministic sensitivity analysis was employed to explore the influence of uncertainty for each input parameter on the incremental cost-effectiveness ratio (ICER). Results: Based on the ICER threshold of €30,030 per quality-adjusted life year (QALY) recommended by the Slovak Ministry of Health, Heberprot-P therapy plus GWC is not a cost-effective alternative to GWC alone over a 10-year time horizon. The ICER increases if a longer time horizon is applied, as the incremental costs are similar, but the aggregated utility gain from avoided amputation is lower. Based on the sensitivity analysis, the utility multiplier for the health state “no ulcer after small amputation” had the most impact on the ICER; however, the model was robust to changes in all input parameters. Conclusions: Heberprot-P, as an add-on therapy to GWC in the treatment of advanced diabetic foot ulcer, is not a cost-effective alternative to GWC alone. However, if the unit cost of Heberprot-P were to be reduced to <€273, its ICER would be <€30,030
Regional effect on urban atmospheric nucleation
Secondary aerosol particle production via new particle formation (NPF) has been shown to be a major contributor to the global aerosol load. NPF has also been observed frequently in urban environments. Here, we investigate the effect of regional NPF on urban aerosol load under well-defined atmospheric conditions. The Carpathian Basin, the largest orogenic basin in Europe, represents an excellent opportunity for exploring these interactions. Based on long-term observations, we revealed that NPF seen in a central large city of the basin (Budapest) and its regional background occur in a consistent and spatially coherent way as a result of a joint atmospheric phenomenon taking place on large horizontal scales. We found that NPF events at the urban site are usually delayed by > 1 h relative to the rural site or even inhibited above a critical condensational sink level. The urban processes require higher formation rates and growth rates to be realized, by mean factors of 2 and 1.6, respectively, than the regional events. Regional-and urban-type NPF events sometimes occur jointly with multiple onsets, while they often exhibit dynamic and timing properties which are different for these two event types.Peer reviewe
Estimating the solar wind pressure at comet 67P from Rosetta magnetic field measurements
Aims: The solar wind pressure is an important parameter of space weather, which plays a crucial role in the interaction of the solar wind with the planetary plasma environment. Here we investigate the possibility of determining a solar wind pressure proxy from Rosetta magnetic field data, measured deep inside the induced magnetosphere of comet 67P/Churyumov-Gerasimenko. This pressure proxy would be useful not only for other Rosetta related studies but could also serve as a new, independent input database for space weather propagation to other locations in the Solar System.
Method: For the induced magnetospheres of comets the magnetic pressure in the innermost part of the pile-up region is balanced by the solar wind dynamic pressure. Recent investigations of Rosetta data have revealed that the maximum magnetic field in the pile-up region can be approximated by magnetic field measurements performed in the inner regions of the cometary magnetosphere, close to the boundary of the diamagnetic cavity, from which the external solar wind pressure can be estimated.
Results: We were able to determine a solar wind pressure proxy for the time interval when the Rosetta spacecraft was located near the diamagnetic cavity boundary, between late April 2015 and January 2016. We then compared our Rosetta pressure proxy to solar wind pressure extrapolated to comet 67P from near-Earth. After the exclusion of disturbances caused by transient events, we found a strong correlation between the two datasets
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