Comment on Y. Couder and E. Fort: "Single-Particle Diffraction and Interference at a Macroscopic Scale", Phys. Rev. Lett. (2006)

In a paper from 2006, Couder and Fort [1] describe a version of the famous double slit experiment performed with drops bouncing on a vibrated fluid surface, where interference in the particle statistics is found even though it is possible to determine unambiguously which slit the "walking" drop passes. It is one of the first papers in an impressive series, showing that such walking drops closely resemble de Broglie waves and can reproduce typical quantum phenomena like tunneling and quantized states [2-13]. The double slit experiment is, however, a more stringent test of quantum mechanics, because it relies upon superposition and phase coherence. In the present comment we first point out that the experimental data presented in [1] are not convincing, and secondly we argue that it is not possible in general to capture quantum mechanical results in a system, where the trajectory of the particle is well-defined.Comment: 4 pages, 1 figur

In vivo efficacy of carvacrol on Campylobacter jejuni prevalence in broiler chickens during an entire fattening period

Carvacrol, a primary constituent of plant essential oils (EOs), and its antimicrobial activity have been the subject of many in vitro studies. Due to an increasing demand for alternative antimicrobials and an emerging number of antibiotic resistant bacteria, the use of essential oils has played a major role in many recent approaches to reduce Campylobacter colonization in poultry before slaughter age. For that purpose, the reducing effect of carvacrol on Campylobacter jejuni prevalence in broilers was determined in vivo in an experimental broiler chicken model during an entire fattening period. Carvacrol was added to the feed in a concentration of 120 mg/kg feed four days post hatch until the end of the trial. In this study, we demonstrated a statistically significant decrease of C. jejuni counts by 1.17 decadic logarithm (log10) most probable number (MPN)/g in cloacal swabs during starter and grower periods (corresponding to a broilers age between 1 and 28 days). Similar results were observed for colon enumeration at the end of the trial where C. jejuni counts were significantly reduced by 1.25 log10 MPN/g. However, carvacrol did not successfully reduce Campylobacter cecal colonization in 33-day-old broilers

Cryo-Preparation and Planar Magnetron Sputtering for Low Temperature Scanning Electron Microscopy

Cryo-preparation is a reliable technique for the structural investigation of food products in low temperature scanning electron microscopy (SEM). Artifacts, such as, the segregation of water/non-water ingredients, occur during the freezing process by the crystallization of ice; they can be helpful for correct interpretation of visualized details, e.g., the detection of water containing compartments. The size of the segregation structures depends on water concentration and specimen thickness. The condensation of water vapor (ice contamination) is influenced by the specimen temperature and the partial pressure of the water inside the vacuum system. Furthermore, the evaporation (sublimation, etching) of specimen water can be regulated by monitoring the specimen temperature. Sublimation under SEM observation, i.e., in situ etching at low acceleration voltage, allows the progress of etching to be observed continuously, prior to the coating of the specimen inside a dedicated cryo-preparation system attached to the SEM. Coating of specimens provides superior structural resolution compared with the observation of uncoated samples. A coating layer of platinum ( ~ 1-2 nm thick), deposited on a cold substrate by planar magnetron sputtering, is almost homogenous and has a density close to that of the solid metal. Its use allows bulk biological specimens to be observed in low temperature SEM with a structural resolution up to the visualization of transmembrane proteins

The influence of the working conditions on the equilibrium factor F and the unattached fraction fp

We report on the influence of the working conditions on the dose estimation. Especially the equilibrium factor and the unattached fraction are influenced by the working conditions. For instance in a cabinet-maker’s shop the radon concentration is strongly influenced by the ventilation system. The factor F is influenced by dust-producing work processes. For a better knowledge of the radon dosimetry it is also necessary to measure continuously and separately the unattached fraction of the radon progeny. We present first results obtained with a SARAD EQF 3020 monitor which contains three alpha detector microsystems measuring radon in the air, attached radon daughters and unattached radon daughters. The three components are measured quasicontinuously with a temporal resolution of 2 hours. The measuring range is 1 to 10 MBq/m3 at a low detection limit of 0.1 Bq/m3 equivalent radon concentration. The system was tested in buildings, caves, mines, waterworks and other places. By using silicon microsystems with alpha detector, ADC, memory and logics—which are integrated on few chips—the costs for the production of equipment are far lower than if produced by means of assembled individual components