Fluctuations in viscous fingering

Our experiments on viscous (Saffman-Taylor) fingering in Hele-Shaw channels reveal finger width fluctuations that were not observed in previous experiments, which had lower aspect ratios and higher capillary numbers Ca. These fluctuations intermittently narrow the finger from its expected width. The magnitude of these fluctuations is described by a power law, Ca^{-0.64}, which holds for all aspect ratios studied up to the onset of tip instabilities. Further, for large aspect ratios, the mean finger width exhibits a maximum as Ca is decreased instead of the predicted monotonic increase.Comment: Revised introduction, smoothed transitions in paper body, and added a few additional minor results. (Figures unchanged.) 4 pages, 3 figures. Submitted to PRE Rapi

The congested International Match Calendar in football : views of 1055 professional male players

BACKGROUND : The International Match Calendar congestion affects players recovery. The views of a worldwide cohort of professional football players is shared in this communication. METHODS : A cross-sectional observational study recruited players through Fédération Internationale des Associations de Footballeurs Professionnel’s national members. An electronic survey was shared in English, French, Italian and Spanish with 1055 players consenting and completing it anonymously in November 2021. RESULTS : A total of 42% of respondents believe back-to-back matches should be limited to three. Most respondents (69%) felt off or in season breaks are infringed by clubs or national teams and 83% believe regulations should protect them. A total of 55% of players believed they sustained one or more injuries due to the overload and it has affected 52% of respondents’ mental state. CONCLUSION : The congested International Match Calendar poses a risk to professional footballers physical and mental health. Poor recovery between matches may affect player availability and performance. Players should be represented by active players when International Match Calendar scheduling decisions are made. Administrators should seek medical guidance regarding the effects of overload on performance prior to making decisions. This study allows the opportunity for a larger national team player sample to be studied.https://bmcsportsscimedrehabil.biomedcentral.comhj2023Sports Medicin

The ability of Listeria monocytogenes to form biofilm on surfaces relevant to the mushroom production environment

peer-reviewedDue to its ubiquitous nature, Listeria monocytogenes is a threat to all fresh fruits and vegetables, including mushrooms, which are Ireland's largest horticultural crop. Although fresh cultivated mushrooms (Agaricus bisporus) have not been previously linked with listeriosis outbreaks, the pathogen still poses a threat to the industry, particularly due to its ability to form biofilms. This threat is highlighted by the multiple recalls of mushroom products caused by L. monocytogenes contamination and by previous studies demonstrating that L. monocytogenes is present in the mushroom production environment. In this study, the biofilm formation potential of L. monocytogenes strains isolated from the mushroom production environment was investigated on materials and at temperatures relevant to mushroom production. A preliminary assessment of biofilm formation of 73 mushroom industry isolates was undertaken using a crystal violet assay on polystyrene microtitre plates. The biofilm formation of a subset (n = 7) of these strains was then assessed on twelve different materials, including materials that are representative of the materials commonly found in the mushroom production environments, using the CDC biofilm reactor. Vertical scanning interferometry was used to determine the surface roughness of the chosen materials. All the strains tested using the CDC biofilm reactor were able to form biofilms on the different surfaces tested but material type was found to be a key determining factor on the levels of biofilm formed. Stainless steel, aluminium, rubber, polypropylene and polycarbonate were all able to support biofilm levels in the range of 4–4.9 log10 CFU/cm2, for seven different L. monocytogenes strains. Mushroom industry-specific materials, including growing nets and tarpaulins, were found to support biofilms levels between 4.7 and 6.7 log10 CFU/cm2. Concrete was found to be of concern as it supported 7.7 log10 CFU/cm2 of biofilm for the same strains; however, sealing the concrete resulted in an approximately 2-log reduction in biofilm levels. The surface roughness of the materials varied greatly between the materials (0.7–3.5 log10 Ra) and was found to have a positive correlation with biofilm formation (rs = 0.573) although marginally significant (P = 0.051). The results of this study indicate that L. monocytogenes can readily form biofilms on mushroom industry relevant surfaces, and additionally identifies surfaces of specific concern, where rigorous cleaning and disinfection is required

Path integral duality and Planck scale corrections to the primordial spectrum in exponential inflation

The enormous red-shifting of the modes during the inflationary epoch suggests that physics at the Planck scale may modify the standard, nearly, scale-invariant, primordial, density perturbation spectrum. Under the principle of path-integral duality, the space-time behaves as though it has a minimal length $L_{_{\rm P}}$ (which we shall assume to be of the order of the Planck length), a feature that is expected to arise when the quantum gravitational effects on the matter fields have been taken into account. Using the method of path integral duality, in this work, we evaluate the Planck scale corrections to the spectrum of density perturbations in the case of exponential inflation. We find that the amplitude of the corrections is of the order of $({\cal H}/M_{_{\rm P}})$, where ${\cal H}$ and $M_{_{\rm P}}$ denote the inflationary and the Planck energy scales, respectively. We also find that the corrections turn out to be completely independent of scale. We briefly discuss the implications of our result, and also comment on how it compares with an earlier result.Comment: 12 pages, 1 figure, RevTex4 forma

Effectiveness of current hygiene practices on minimization of Listeria monocytogenes in different mushroom production‐related environments

peer-reviewedBackground: The commercial production of Agaricus bisporus is a three stage process: 1) production of compost, also called “substrate”; 2) production of casing soil; and 3) production of the mushrooms. Hygiene practices are undertaken at each stage: pasteurization of the substrate, hygiene practices applied during the production of casing soil, postharvest steam cookout, and disinfection at the mushroom production facilities. However, despite these measures, foodborne pathogens, including Listeria monocytogenes, are reported in the mushroom production environment. In this work, the presence of L. monocytogenes was evaluated before and after the application of hygiene practices at each stage of mushroom production with swabs, samples of substrate, casing, and spent mushroom growing substrates. Results: L. monocytogenes was not detected in any casing or substrate sample by enumeration according to BS EN ISO 11290-2:1998. Analysis of the substrate showed that L. monocytogenes was absent in 10 Phase II samples following pasteurization, but was then present in 40% of 10 Phase III samples. At the casing production facility, 31% of 59 samples were positive. Hygiene improvements were applied, and after four sampling occasions, 22% of 37 samples were positive, but no statistically significant difference was observed (p > .05). At mushroom production facilities, the steam cookout process inactivated L. monocytogenes in the spent growth substrate, but 13% of 15 floor swabs at Company 1 and 19% of 16 floor swabs at Company 2, taken after disinfection, were positive. Conclusion: These results showed the possibility of L. monocytogenes recontamination of Phase III substrate, cross-contamination at the casing production stage and possible survival after postharvest hygiene practices at the mushroom growing facilities. This information will support the development of targeted measures to minimize L. monocytogenes in the mushroom industry.Food Institutional Research Measur

Quality of mother-child interaction, differences in sexual attitudes, and inter-generational disagreement on sexuality.

The current paper examines the frequency of inter-generational disagreement reported by mothers and adolescents as a function of the quality of their interaction, and the match between their sexual attitudes. We expected that the quality of family interaction would act as a "family asset" that would enable members of families to manage and control the tensions caused by differences in (sexual) attitudes. Data on 319 British adolescent-mother pairs were analysed using structural equation modelling, revealing good support for these expectations: differences in sexual attitudes were more strongly linked to inter-family disagreement in low quality of mother-child interaction families than in high quality of motherchild interaction families. Implications of the study are discussed. © 1997 OPA (Overseas Publishers Association)

Decoherence and CPT Violation in a Stringy Model of Space-Time Foam

I discuss a model inspired from the string/brane framework, in which our Universe is represented as a three brane, propagating in a bulk space time punctured by D0-brane (D-particle) defects. As the D3-brane world moves in the bulk, the D-particles cross it, and from an effective observer on D3 the situation looks like a ``space-time foam'' with the defects ``flashing'' on and off (``D-particle foam''). The open strings, with their ends attached on the brane, which represent matter in this scenario, can interact with the D-particles on the D3-brane universe in a topologically non-trivial manner, involving splitting and capture of the strings by the D0-brane defects. Such processes are described by logarithmic conformal field theories on the world-sheet. Physically, they result in effective decoherence of the string matter on the D3 brane, and as a result, of CPT Violation, but of a type that implies an ill-defined nature of the effective CPT operator. Due to electric charge conservation, only electrically neutral (string) matter can exhibit such interactions with the D-particle foam. This may have unique, experimentally detectable, consequences for electrically-neutral entangled quantum matter states on the brane world, in particular the modification of the pertinent EPR Correlation of neutral mesons in a meson factory.Comment: 41 pages Latex, five eps figures incorporated. Uses special macro

IceCube - the next generation neutrino telescope at the South Pole

IceCube is a large neutrino telescope of the next generation to be constructed in the Antarctic Ice Sheet near the South Pole. We present the conceptual design and the sensitivity of the IceCube detector to predicted fluxes of neutrinos, both atmospheric and extra-terrestrial. A complete simulation of the detector design has been used to study the detector's capability to search for neutrinos from sources such as active galaxies, and gamma-ray bursts.Comment: 8 pages, to be published with the proceedings of the XXth International Conference on Neutrino Physics and Astrophysics, Munich 200

Muon Track Reconstruction and Data Selection Techniques in AMANDA

The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ice between 1500m and 2000m. The primary goal of this detector is to discover astrophysical sources of high energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector. The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2 degree accuracy.Comment: 40 pages, 16 Postscript figures, uses elsart.st