Logistiek management marketing-instrument van de jaren negentig

Logistics;produktieleer/ produktieplanning

Mapping individual electromagnetic field components inside a photonic crystal

We present a method to map the absolute electromagnetic field strength inside photonic crystals. We apply the method to map the electric field component Ez of a two-dimensional photonic crystal slab at microwave frequencies. The slab is placed between two mirrors to select Bloch standing waves and a subwavelength spherical scatterer is scanned inside the resulting resonator. The resonant Bloch frequencies shift depending on the electric field at the position of the scatterer. To map the electric field component Ez we measure the frequency shift in the reflection and transmission spectrum of the slab versus the scatterer position. Very good agreement is found between measurements and calculations without any adjustable parameters.Comment: 12 pages, 7 figure

In search of virus carriers of the 1988 and 2002 phocine distemper virus outbreaks in European harbour seals

European harbour seal (Phoca vitulina) populations decreased substantially during the phocine distemper virus (PDV) outbreaks of 1988 and 2002. Different hypotheses have stated that various seals and terrestrial carnivore species might be the source of infection. To further analyse these hypotheses, grey (Halichoerus grypus) and ringed (Phoca hispida) seals, polar bears (Ursus maritimus) and minks (Mustela lutreola) were sampled from the North Sea and East Greenland coasts between 1988 and 2004 and investigated by RT-PCR using a panmorbillivirus primer pair. However, all samples were negative for morbillivirus nucleic acid

Raman study of the phonon symmetries in BiFeO3_3 single crystals

In bismuth ferrite (BiFeO3), antiferromagnetic and ferroelectric order coexist at room temperature, making it of particular interest for studying magnetoelectric coupling. The mutual control of magnetic and electric properties is very useful for a wide variety of applications. This has led to an enormous amount of research into the properties of BiFeO$_3$. Nonetheless, one of the most fundamental aspects of this material, namely the symmetries of the lattice vibrations, remains controversial.We present a comprehensive Raman study of BiFeO$_3$ single crystals with the approach of monitoring the Raman spectra while rotating the polarization direction of the excitation laser. Our method results in unambiguous assignment of the phonon symmetries and explains the origin of the controversy in the literature. Furthermore, it provides access to the Raman tensor elements enabling direct comparison with theoretical calculations. Hence, this allows the study of symmetry breaking and coupling mechanisms in a wide range of complex materials and may lead to a noninvasive, all-optical method to determine the orientation and magnitude of the ferroelectric polarization.Comment: 5 pages, 4 figures, 1 tabl

Measurement of the temperature of an ultracold ion source using time-dependent electric fields

We report on a measurement of the characteristic temperature of an ultracold rubidium ion source, in which a cloud of laser-cooled atoms is converted to ions by photo-ionization. Extracted ion pulses are focused on a detector with a pulsed-field technique. The resulting experimental spot sizes are compared to particle-tracking simulations, from which a source temperature $T = (1 \pm 2)$ mK and the corresponding transversal reduced emittance $\epsilon_r = 7.9 X 10^{-9}$ m rad $\sqrt{\rm{eV}}$ are determined. We find that this result is likely limited by space charge forces even though the average number of ions per bunch is 0.022.Comment: 8 pages, 11 figure

Treatment options in extra-articular distal radius fractures:a systematic review and meta-analysis

PURPOSE: This systematic literature review aimed to make a detailed overview on the clinical and functional outcomes and to get insight into the possible superiority of a treatment method for extra-articular distal radius fractures. METHODS: Embase, Medline, Cochrane Library, Web of Science, and Google Scholar were searched for studies describing treatment results. Five treatment modalities were compared: plaster cast immobilization, K-wire fixation, volar plating, external fixation, and intramedullary fixation. RESULTS: Out of 7,054 screened studies, 109 were included in the analysis. Overall complication rate ranged from 9% after plaster cast treatment to 18.5% after K-wire fixation. For radiographic outcomes, only volar tilt in the plaster cast group was lower than in the other groups. Apart from better grip strength after volar plating, no clear functional differences were found across treatment groups. CONCLUSION: Current literature does not provide uniform evidence to prove superiority of a particular treatment method when looking at complications, re-interventions, and long-term functional outcomes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00068-021-01679-z