Drie nieuwe Ponto-Kaspische inwijkelingen dringen door tot in kanalen in de provincie Antwerpen: De zoetwaterpolychaet <i>Hypania invalida</i> (Grube, 1860) en, voor het eerst in België, de platworm <i>Dendrocoelum romanodanubiale</i> (Codreanu, 1949) en de Donaupissebed <i>Jaera istri</i> Veuille, 1979

Since 2000 three Ponto-Caspian invaders have been found in canals in the province of Antwerp (N.E.-Belgium): the freshwater polychaete Hypania invalida (Grube, 1860), the triclad Dendrocoelum romanodanubiale (Codreanu, 1949) and the freshwater isopod Jaera istri Veuille, 1979. Staff members of the 'Vlaamse Milieumaatschappij (Flemish Environmental Agency) collected these species on artificial substrates (nets filled with broken bricks). H. invalida had been discovered before in Belgium in the river Meuse in 2000 (Vanden Bossche et.al., 2001). D. romanodanubiale and J. istri were never recorded before in Belgium. Before its discovery in the Belgian Meuse in August-September 2000, H.invalida had already been found in May 2000 in the Albert Canal at Genk in the province of Limbourg. Between 2001 and 2003, the polychaete was sampled at several stations of the Albert Canal and its adjacent canals in the provinces of Antwerp and Limbourg. Here, it often is accompanied by D. romanodanubiale and J. istri. In 2003 the polychaet had also been encountered in the Sea canal Brussels - Scheldt in the province of Antwerp. The discontinuous distribution indicates that navigation plays an important role in the dispersal of the species. Other Ponto-Caspian species such as Dikerogammarus villosus (Sovinskij, 1894) are either already present in the canals or soon to be expected there. Some of these species will probably also invade the Scheldt basin

Direct magneto-optical compression of an effusive atomic beam for high-resolution focused ion beam application

An atomic rubidium beam formed in a 70 mm long two-dimensional magneto-optical trap (2D MOT), directly loaded from a collimated Knudsen source, is analyzed using laser-induced fluorescence. The longitudinal velocity distribution, the transverse temperature and the flux of the atomic beam are reported. The equivalent transverse reduced brightness of an ion beam with similar properties as the atomic beam is calculated because the beam is developed to be photoionized and applied in a focused ion beam. In a single two-dimensional magneto-optical trapping step an equivalent transverse reduced brightness of $(1.0\substack{+0.8-0.4})$ $\times 10^6$ A/(m$^2$ sr eV) was achieved with a beam flux equivalent to $(0.6\substack{+0.3-0.2})$ nA. The temperature of the beam is further reduced with an optical molasses after the 2D MOT. This increased the equivalent brightness to $(6\substack{+5-2})$$\times 10^6$ A/(m$^2$ sr eV). For currents below 10 pA, for which disorder-induced heating can be suppressed, this number is also a good estimate of the ion beam brightness that can be expected. Such an ion beam brightness would be a six times improvement over the liquid metal ion source and could improve the resolution in focused ion beam nanofabrication.Comment: 10 pages, 8 figures, 1 tabl

Separation of Time Scales in a Quantum Newton’s Cradle

We provide detailed modeling of the Bragg pulse used in quantum Newton’s-cradle-like settings or in Bragg spectroscopy experiments for strongly repulsive bosons in one dimension. We reconstruct the postpulse time evolution and study the time-dependent local density profile and momentum distribution by a combination of exact techniques. We further provide a variety of results for finite interaction strengths using a time-dependent Hartree-Fock analysis and bosonization-refermionization techniques. Our results display a clear separation of time scales between rapid and trap-insensitive relaxation immediately after the pulse, followed by slow in-trap periodic behavior

The arthroscopic treatment of displaced tibial spine fractures in children and adolescents using Meniscus Arrows®

This article summarises the results of a newly developed technique that utilises Meniscus Arrows(A (R)) for the arthroscopic fixation of displaced tibial spine fractures in children and adolescents. Twelve tibial spine fractures in the knees of eleven children between 6 and 15 years old, with an average age of 12 years, were arthroscopically fixed with Meniscus Arrows(A (R)), after a reduction of their fractures. This was followed by 5 weeks immobilisation in a plaster of Paris. Postoperative follow-up included radiographs, Lachmann tests on all of the children's knees and KT-1000 tests of eight out of twelve of the children's knees. The postoperative follow-up time ranged from 3 to 10 years, with patients being seen for an average of 4 years. All of the fractures consolidated uneventfully, and all of the patients returned unrestricted to their previous activity level. The Lachmann tests revealed no, or a non-functional, laxity in any of the patients' knees. The KT-1000 tests showed a difference between the operated side, and non-operated side, of between 3 mm in the first knee operated on and an average of 1 mm in the remaining knees. The arthroscopic fixation of tibial spine fractures using Meniscus Arrows(A (R)) showed that this minimally invasive procedure resulted in the uneventful consolidation of all twelve of the fractures, with excellent results, and without the need for a second, hardware removal, operation. Level of Evidence: Level IV

Cumulant theory of the unitary Bose gas: Prethermal and Efimovian dynamics

We study the quench of a degenerate ultracold Bose gas to the unitary regime, where interactions are as strong as allowed by quantum mechanics. We lay the foundations of a cumulant theory able to capture simultaneously the three-body Efimov effect and ergodic evolution. After an initial period of rapid quantum depletion, a universal prethermal stage is established characterized by a kinetic temperature and an emergent Bogoliubov dispersion law while the microscopic degrees of freedom remain far-from-equilibrium. Integrability is then broken by higher-order interaction terms in the many-body Hamiltonian, leading to a momentum-dependent departure from power law to decaying exponential behavior of the occupation numbers at large momentum. We find also signatures of the Efimov effect in the many-body dynamics and make a precise identification between the observed beating phenomenon and the binding energy of an Efimov trimer. Throughout the work, our predictions for a uniform gas are quantitatively compared with experimental results for quenched unitary Bose gases in uniform potentials.Comment: 34 pages, 12 figure

Cytophagic histiocytic panniculitis: is it a macrophage activation syndrome in situ?

International audiencepas de résum

Sculpting oscillators with light within a nonlinear quantum fluid

Seeing macroscopic quantum states directly remains an elusive goal. Particles with boson symmetry can condense into such quantum fluids producing rich physical phenomena as well as proven potential for interferometric devices [1-10]. However direct imaging of such quantum states is only fleetingly possible in high-vacuum ultracold atomic condensates, and not in superconductors. Recent condensation of solid state polariton quasiparticles, built from mixing semiconductor excitons with microcavity photons, offers monolithic devices capable of supporting room temperature quantum states [11-14] that exhibit superfluid behaviour [15,16]. Here we use microcavities on a semiconductor chip supporting two-dimensional polariton condensates to directly visualise the formation of a spontaneously oscillating quantum fluid. This system is created on the fly by injecting polaritons at two or more spatially-separated pump spots. Although oscillating at tuneable THz-scale frequencies, a simple optical microscope can be used to directly image their stable archetypal quantum oscillator wavefunctions in real space. The self-repulsion of polaritons provides a solid state quasiparticle that is so nonlinear as to modify its own potential. Interference in time and space reveals the condensate wavepackets arise from non-equilibrium solitons. Control of such polariton condensate wavepackets demonstrates great potential for integrated semiconductor-based condensate devices.Comment: accepted in Nature Physic

Early weight measures and long-term neuropsychological outcome of critically ill neonates and infants:a secondary analysis of the PEPaNIC trial

Neonates and infants surviving critical illness show impaired growth during critical illness and are at risk for later neuropsychological impairments. Early identification of individuals most at risk is needed to provide tailored long-term follow-up and care. The research question is whether early growth during hospitalization is associated with growth and neuropsychological outcomes in neonates and infants after pediatric intensive care unit admission (PICU). This is a secondary analysis of the PEPaNIC trial. Weight measurements upon PICU admission, at PICU discharge, at hospital discharge, at 2- and 4-year follow-up, and of different subgroups were compared using (paired) t-tests. Multiple linear regression analyses were performed to investigate the association between early growth in weight measures and neuropsychological outcomes at 4-year follow-up. One hundred twenty-one infants were included, and median age upon admission was 21 days. Growth in weight per week was less than the age-appropriate norm, resulting in a decrease in weight-for-age Z-score during hospitalization. Weight is normalized at 2- and 4-year follow-up. Weight gain in kilograms per week and change in weight Z-score were not associated with neurodevelopmental outcome measures at 4-year follow-up. Lower weight-for-age Z-score at PICU admission and at hospital discharge was associated only with lower weight and height Z-scores at 4-year follow-up. Conclusion: Growth in weight during hospital stay of young survivors of critical illness is impaired. Worse early growth in weight is associated with lower weight and height but not with neuropsychological outcomes at 4-year follow-up. What is Known: • Critically ill neonates and infants show impaired early growth during admission and are at risk for later neuropsychological impairments. • Unraveling the association between early growth and later neuropsychological impairments is crucial since the first year of life is critical for brain development. What is New: • Critically ill neonates and infants had age appropriate weight measures at 4-year follow-up. • Poor growth in weight during hospital stay was not associated with poorer cognitive, emotional, or behavioral functioning four years after critical illness.</p

Differences in enteric neuronal density in the NSE-Noggin mouse model across institutes

The enteric nervous system (ENS) is a large and complex part of the peripheral nervous system, and it is vital for gut homeostasis. To study the ENS, different hyper- and hypo-innervated model systems have been developed. The NSE-Noggin mouse model was described as one of the few models with a higher enteric neuronal density in the colon. However, in our hands NSE-Noggin mice did not present with a hyperganglionic phenotype. NSE-Noggin mice were phenotyped based on fur appearance, genotyped and DNA sequenced to demonstrate transgene and intact NSE-Noggin-IRES-EGFP construct presence, and RNA expression of Noggin was shown to be upregulated. Positive EGFP staining in the plexus of NSE-Noggin mice also confirmed Noggin protein expression. Myenteric plexus preparations of the colon were examined to quantify both the overall density of enteric neurons and the proportions of enteric neurons expressing specific subtype markers. The total number of enteric neurons in the colonic myenteric plexus of transgenic mice did not differ significantly from wild types, nor did the proportion of calbindin, calretinin, or serotonin immunoreactive myenteric neurons. Possible reasons as to why the hyperinnervated phenotype could not be observed in contrast with original studies using this mouse model are discussed, including study design, influence of microbiota, and other environmental variables.</p