Theory of Feshbach molecule formation in a dilute gas during a magnetic field ramp

Starting with coupled atom-molecule Boltzmann equations, we develop a simplified model to understand molecule formation observed in recent experiments. Our theory predicts several key features: (1) the effective adiabatic rate constant is proportional to density; (2) in an adiabatic ramp, the dependence of molecular fraction on magnetic field resembles an error function whose width and centroid are related to the temperature; (3) the molecular production efficiency is a universal function of the initial phase space density, the specific form of which we derive for a classical gas. Our predictions show qualitative agreement with the data from [Hodby et al, Phys. Rev. Lett. {\bf{94}}, 120402 (2005)] without the use of adjustable parameters

Ranking of food safety risks in pork from organic and free-range production systems

The objectives of this semi-quantitative risk assessment were to identify, assess and rank food safety risks in outdoor pig production (organic and free-range) compared to indoor pig production (conventional) in Denmark. In addition, high-risk pork products would be identified. Finally, risk-reducing strategies for handling the identified agents would be suggested. Data were obtained from the literature as well as in-house statistics. Data describing tetracycline-resistant E. coli in outdoor pigs were available from the Qualysafe project. The OIE framework for risk assessment was applied

Electron-ion Recombination In Gas Mixtures Of Helium, Nitrogen, And Carbon Dioxide

A study has been conducted to determine the electron-ion recombination rates in gas mixtures of helium, nitrogen, and carbon dioxide. Measurements were made as functions of electric field strength, gas pressure, and gas composition. In gas mixtures containing only nitrogen and carbon dioxide, the rates were dependent on pressure. This dependence is interpreted as being due to the separate effects of two- and three-body recombination processes. No pressure dependence was observed for mixtures containing helium. In such mixtures, two-body recombination appears to be dominant. Moreover, the addition of relatively low concentrations of helium to the discharge leads to a dramatic change in the bulk recombination rate. Two possible explanations for this observation are suggested. © 1984 American Institute of Physics

Notes on Danish Scientific Work Since 1939

Brief tabulated information on personnel, program, and locality of field investigations in Greenland on: geology by A. Noe-Nygaard, zoology by C. Vibe, botany by T.W. Bocher, and archeology by E. Holtved. Includes note on Geological Survey of Greenland, established 1946

Superconductivity enhanced conductance fluctuations in few layer graphene nanoribbons

We investigate the mesoscopic disorder induced rms conductance variance $\delta G$ in a few layer graphene nanoribbon (FGNR) contacted by two superconducting (S) Ti/Al contacts. By sweeping the back-gate voltage, we observe pronounced conductance fluctuations superimposed on a linear background of the two terminal conductance G. The linear gate-voltage induced response can be modeled by a set of inter-layer and intra-layer capacitances. $\delta G$ depends on temperature T and source-drain voltage $V_{sd}$. $\delta G$ increases with decreasing T and $|V_{sd}|$. When lowering $|V_{sd}|$, a pronounced cross-over at a voltage corresponding to the superconducting energy gap $\Delta$ is observed. For |V_{sd}|\ltequiv \Delta the fluctuations are markedly enhanced. Expressed in the conductance variance $G_{GS}$ of one graphene-superconducutor (G-S) interface, values of 0.58 e^2/h are obtained at the base temperature of 230 mK. The conductance variance in the sub-gap region are larger by up to a factor of 1.4-1.8 compared to the normal state. The observed strong enhancement is due to phase coherent charge transfer caused by Andreev reflection at the nanoribbon-superconductor interface.Comment: 15 pages, 5 figure

Maternal allergen immunisation to prevent sensitisation in offspring: Th2-polarising adjuvants are more efficient than a Th1-polarising adjuvant in mice

<p>Abstract</p> <p>Background</p> <p>Allergy has been an increasing problem in several parts of the world. Prenatal exposure to allergen and microbial components may affect the development of allergies in childhood, as indicated by epidemiological and experimental studies. We investigated the capacity for allergic sensitisation in offspring after induction of a Th1- or a Th2-polarised immune response to the same allergen in mothers during pregnancy.</p> <p>Results</p> <p>During pregnancy, mice were immunised with ovalbumin (OVA) given with either one of the Th2-adjuvants pertussis toxin (PT) or Al(OH)₃(aluminium hydroxide), or with the Th1 adjuvant CpG. Offspring were immunised with OVA in Al(OH)₃as young adults. Serum and supernatants from <it>ex vivo </it>stimulated or non-stimulated spleen cells from mothers and offspring were analysed for OVA-specific antibodies and cytokines, respectively. Mothers immunised with OVA together with either Al(OH)₃or PT had increased levels of OVA-specific IgE and IgG1 compared to naive mothers, whereas mothers immunised with OVA together with CpG had increased levels of OVA-specific IgG2a compared to naive mothers. In general the highest levels of IL-5, IL-10, and IFNγ were observed in spleen cells from mothers immunised with PT and OVA. Upon immunisation, offspring from mothers immunised with OVA and either PT or Al(OH)₃showed reduced levels of OVA-specific IgE and IgG1 and increased levels of OVA-specific IgG2a antibodies compared to offspring from naive mothers. Maternal immunisation with CpG and OVA did not affect antibody responses in offspring.</p> <p>Conclusion</p> <p>Allergic sensitisation in the offspring was affected by the type of adjuvant used for immunisation of the mothers with the same allergen. Th2 polarisation of the immune response in the mothers was found to give reduced IgE levels upon sensitisation of the offspring, whereas no reduction was achieved with Th1 polarisation in the mothers.</p

Vortex line in a neutral finite-temperature superfluid Fermi gas

The structure of an isolated vortex in a dilute two-component neutral superfluid Fermi gas is studied within the context of self-consistent Bogoliubov-de Gennes theory. Various thermodynamic properties are calculated and the shift in the critical temperature due to the presence of the vortex is analyzed. The gapless excitations inside the vortex core are studied and a scheme to detect these states and thus the presence of the vortex is examined. The numerical results are compared with various analytical expressions when appropriate.Comment: 8 pages, 6 embedded figure