359 research outputs found
Quantum-limited mass flow of liquid ³He
We consider theoretically the possibility of observing unusual quantum fluid behavior in liquid ³He and
solutions of ³He in ⁴He systems confined to nano-channels. In the case of pure ballistic flow at very low
temperature conductance will be quantized in units of 2 m²/h. We show that these steps should be sensitive to
increases in temperature. We also use a random scattering matrix simulation to study flow with diffusive
wall scattering. Universal conductance fluctuations analogous to those seen in electron systems should then
be observable. Finally we consider the possibility of the cross-over to a one-dimensional system at sufficiently
low temperature where the system could form a Luttinger liquid
Size-effects in the Density of States in NS and SNS junctions
The quasiparticle local density of states (LDOS) is studied in clean NS and
SNS junctions with increasing transverse size, from quasi-one-dimensional to
three-dimensional. It is shown that finite transverse dimensions are related to
pronounced effects in the LDOS, such as fast oscillations superimposed on the
quasiparticle interference oscillations (for NS) and additional peaks in the
bound state spectrum in the subgap region (for SNS). Also, the validity of the
Andreev approximation is discussed. It turns out to be an acceptable
approximation in all situations tested.Comment: 9 pages, RevTex, 5 figures, accepted in Phys. Rev.
Detection of antibacterial activity of essential oil components by TLC-bioautography using luminescent bacteria
The aim of the present study was the chemical characterization of some medically relevant essential oils (tea tree, clove, cinnamon bark, thyme and eucalyptus) and the investigation of antibacterial effect of the components of these oils by use of a direct bioautographic method. Thin layer chromatography (TLC) was combined with biological detection in this process. The chemical composition of the oils was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Eucalyptol (84.2%) was the main component of the essential oil of eucalyptus, eugenol (83.7%) of clove oil, and trans-cinnamic aldehyde (73.2%), thymol (49.9%) and terpinen-4-ol (45.8%) of cinnamon bark, thyme and tea tree oils, respectively. Antibacterial activity of the separated components of these oils, as well as their pure main components (eucalyptol, eugenol, trans-cinnamic aldehyde and thymol) was observed against the Gram-negative luminescence tagged plant pathogenic bacterium Pseudomonas syringae pv. maculicola (Psmlux) and the Gram-negative, naturally luminescent marine bacterium Vibrio fischeri. On the whole, the antibacterial activity of the essential oils could be related to their main components, but the minor constituents may be involved in this process. Trans-cinnamic aldehyde and eugenol were the most active compounds in TLC-bioautography.
The sensitivity of TLC-bioautographic method can be improved with using luminescent test bacteria. This method is more cost-effective and provides more reliable results in comparison with conventional microbiological methods, e.g. disc-diffusion technique
The Rolling Tachyon as a Matrix Model
We express all correlation functions in timelike boundary Liouville theory as
unitary matrix integrals and develop efficient techniques to evaluate these
integrals. We compute large classes of correlation functions explicitly,
including an infinite number of terms in the boundary state of the rolling
tachyon. The matrix integrals arising here also determine the correlation
functions of gauge invariant operators in two dimensional Yang-Mills theory,
suggesting an equivalence between the rolling tachyon and QCD_2.Comment: 22pages. 3 figures. v2: added reference, fixed minor typo
Study of the production of and hadrons in collisions and first measurement of the branching fraction
The product of the () differential production
cross-section and the branching fraction of the decay () is
measured as a function of the beauty hadron transverse momentum, ,
and rapidity, . The kinematic region of the measurements is and . The measurements use a data sample
corresponding to an integrated luminosity of collected by the
LHCb detector in collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb
results of the fragmentation fraction ratio, , the
branching fraction of the decay is
measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi
pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4},
\end{equation*} where the first uncertainty is statistical, the second is
systematic, the third is due to the uncertainty on the branching fraction of
the decay , and the
fourth is due to the knowledge of . The sum of the
asymmetries in the production and decay between and
is also measured as a function of and .
The previously published branching fraction of , relative to that of , is updated.
The branching fractions of are determined.Comment: 29 pages, 19figures. All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm
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