In-flight measurements of energetic radiation from lightning and thunderclouds

In the certification procedure aircraft builders carry out so-called icing tests flights, where the zero degree Celsius altitude is deliberately sought and crossed in or under thunderstorms. Airbus also used these flights to test ILDAS, a system aimed to determine lightning severity and attachment points during flight from high speed data on the electric and magnetic field at the aircraft surface. We used this unique opportunity to enhance the ILDAS systems with two x-ray detectors coupled to high speed data recorders in an attempt to determine the x-rays produced by lightning in-situ, with synchronous determination of the lightning current distribution and electric field at the aircraft. Such data are of interest in a study of lightning physics. In addition, the data may provide clues to the x-ray dose for personnel and equipment during flights. The icing campaign ran in April 2014; in six flights we collected data of 61 lightning strikes on an Airbus test aircraft. In this communication we briefly describe ILDAS and present selected results on three strikes, two aircraft initiated and one intercepted. Most of the x-rays have been observed synchronous with initiating negative leader steps, and as bursts immediately preceding the current of the recoil process. Those processes include the return stroke. The bursts last one to four micro-second and attain x-ray energies up to 10 MeV. Intensity and spectral distribution of the x-rays and the association with the current distribution are discussed. ILDAS also continuously records x-rays at low resolution in time and amplitude.Comment: 28 pages, 9 figure

Українська шляхта між польським та українським етносами

Appearance and existence of the Ukrainian gentry relates to the traditions of Polish political culture, so during the whole period of its life it was between the Ukrainian and the Polish ethnic groups. Polanisation of the Ukrainian gentry begins at the date when some of the Ukrainian territories become a part of Poland and strengthens after Cossack revolution in the middle and at the end of the 16th century. Especially this process becomes effective at the beginning of the 18th century when a great part of gentry from other Polish lands migrates to Pravoberezhia (right-banked Ukraine). Nevertheless, having captured upper class and partially middle class of the Ukrainian gentry, polanisation mainly influenced consciousness and less religion of the lower class of the Ukrainian gentry. As for ethnoculture and language local gentry was mostly Ukrainian and it assimilated numerous Polish gentlemen-immigrants

Analytical expressions for the conductance noise measured with four circular contacts placed in a square array

In the ideal case, noise measurements with four contacts minimize the contribution of the contact interface. There is a need to characterize conductance noise and noise correction factors for the different geometries provided with four contacts, as already is the case for resistivity measurements with van der Pauw structures. Here, we calculate the noise correction factors for two geometries with a pair of sensors and a pair of current driver electrodes placed in a square array. The first geometry investigated is a very large film compared to the distance L between four circular electrodes, which are placed in a square array far away from the borders of the film. The second is a square-shaped conductive film with side length L and provided with four quarter-circle corner contacts with radius l. The effect of the conductance noise in the film can be observed between current free sensors in a four-point measurement or between current carrying drivers in a two-point measurement. Our analytical expressions are based on approximations to solve the integrals (J·)2dA and |J|4dA for the voltage noise measured across a pair of sensors, SVQ, and across the drivers, SVD, respectively. The first and second integrands represent the squared dot product of the current density and adjoint current density and the modulus of the current density to the fourth power, respectively. The current density J in the samples is due to the current I passing through the driver contacts. The calculated expressions are applicable to samples with thickness tl0.1L. Hence, the disturbances in the neighborhood of the sensors on J and of the drivers on are ignored. Noise correction factors for two- and four-point measurements are calculated for sensors on an equipotential (transversal noise) with the driver contacts on the diagonal of a square and for sensors next to each other on one side of the square with the drivers next to each other on the other side of the square (longitudinal noise). In all cases the noise between the sensors is smaller and less sensitive to the contact size 2l/L than the noise between the drivers. The ratio SVQ/SVD becomes smaller with smaller contact radius l. Smaller sensors give a better suppression of interface noise at the contacts. But overly low 2l/L values result in overly high resistance between the sensors and too strong a contribution of thermal noise at the sensors. Therefore, equations are derived to calculate the current level needed to observe 1/f conductance fluctuations on top of the thermal noise. The results from the calculated analytical expressions show good agreement with experimental results obtained from the noise in carbon sheet resistance and numerical results. Transversal noise measurements on a square sample with corner contacts are recommended to characterize the 1/f noise of the layer. This is due to the increased current densities in the sample compared to the open structure, which result in easier detection of the 1/f on top of the thermal noise. ©2007 American Institute of Physic

Heavy quasiparticles in the ferromagnetic superconductor ZrZn2

We report a study of the de Haas-van Alphen effect in the normal state of the ferromagnetic superconductor ZrZn2. Our results are generally consistent with an LMTO band structure calculation which predicts four exchange-split Fermi surface sheets. Quasiparticle effective masses are enhanced by a factor of about 4.9 implying a strong coupling to magnetic excitations or phonons. Our measurements provide insight in to the mechanism for superconductivity and unusual thermodynamic properties of ZrZn2.Comment: 5 pages, 2 figures (one color

Ferromagnetic Properties of ZrZn2_2

The low Curie temperature (T_C approx 28K) and small ordered moment (M_0 approx 0.17 mu_B f.u.^-1) of ZrZn2 make it one of the few examples of a weak itinerant ferromagnet. We report results of susceptibility, magnetization, resistivity and specific heat measurements made on high-quality single crystals of ZrZn2. From magnetization scaling in the vicinity of T_C (0.001<|T-T_C|/T_C<0.08), we obtain the critical exponents beta=0.52+/-0.05 and delta=3.20+/-0.08, and T_C=27.50+/-0.05K. Low-temperature magnetization measurements show that the easy axis is [111]. Resistivity measurements reveal an anomaly at T_C and a non-Fermi liquid temperature dependence rho(T)=rho_0+AT^n, where n=1.67+/-0.02, for 1<T<14K. The specific heat measurements show a mean-field-like anomaly at T_C. We compare our results to various theoretical models.Comment: submitted to PR

BIM : a methodology to transform business processes into software systems

This manuscript proposes a guiding methodology to obtain a software system that supports the execution of the business processes existing within an organization. The methodology promotes the usage of business process reference models and intends to reduce the implementation time of the software systems. The methodology assumes four distinct phases and several abstraction levels and is applicable both when developing systems from scratch or in re-engineering contexts. The methodology embodies a special phase to handle the diversity of the business processes of an organization. By tailoring process reference models and by considering the characteristics of a specific organization, a proper set of business processes is derived for that organization. Then, we can obtain a suitable information system and implement its automatable parts in a software solution that can run on top of open source software frameworks. We also present four new supporting concepts to the methodology, and a summarized execution of it

Fermi Surface Properties of Low Concentration Cex_{x}La1−x_{1-x}B6_{6}: dHvA

The de Haas-van Alphen effect is used to study angular dependent extremal areas of the Fermi Surfaces (FS) and effective masses of Ce$_{x}$La$_{1-x}$B$_{6}$ alloys for $x$ between 0 and 0.05. The FS of these alloys was previously observed to be spin polarized at low Ce concentration ($x$ = 0.05). This work gives the details of the initial development of the topology and spin polarization of the FS from that of unpolarized metallic LaB$_{6}$ to that of spin polarized heavy Fermion CeB$_{6}$ .Comment: 7 pages, 9 figures, submitted to PR

Randomized controlled trial of vacuum therapy for intermittent claudication

OBJECTIVE: The "gold standard" treatment of intermittent claudication (IC) is supervised exercise therapy (SET). Intermittent vacuum therapy (IVT) has recently been promoted as an additional treatment of IC. During IVT, negative pressure and atmospheric pressure are alternatingly applied to the lower extremities, possibly resulting in improved circulation. The aim of this study was to determine a potential additional effect of IVT in IC patients undergoing a standardized SET program. METHODS: IC patients were recruited from three Dutch general hospitals between December 2015 and July 2017. They received a standardized SET program but were also randomly assigned to an intervention group receiving an IVT treatment (-50 mBar negative pressure) or a control group receiving a sham treatment (-5 mBar negative pressure). IVT was provided in a dedicated clinic during 12 sessions of 30 minutes during a 6-week period. The primary outcome measure was a change in maximal treadmill walking distance. Secondary outcome measures were a change in functional treadmill walking distance, 6-minute walk test, ambulatory ability, and quality of life. RESULTS: A total of 78 patients were randomized, of whom 70 were available for intention-to-treat analysis (control, n = 34; intervention, n = 36). At 6 and 12 weeks, increases in walking distance were of equal magnitude. Median (interquartile range) change in maximal treadmill walking distance during 12 weeks was +335 (205-756) meters in control patients and +250 (77-466) meters in intervention patients (P = .109), whereas functional treadmill walking distance increased +230 (135-480) meters and +188 (83-389) meters (P = .233), respectively. Mean ± standard deviation change in the 6-minute walk test was +36 ± 48 meters and +55 ± 63 meters (P = .823), respectively. Ambulatory ability and quality of life improved equally in both groups. CONCLUSIONS: IVT does not confer any additional beneficial effects in IC patients undergoing a standardized SET program