4,680 research outputs found
Growth of aerobic and anaerobic bacteria in agar subjected to freezing and diurnal freezing and thawing
Aerobic and anaerobic bacteria growth in agar after freezing and diurnal freezing and thawin
Sampling and handling of desert soils
Sampling and handling of desert soils - area site, transportation, processing, and storag
Electrodeposition in capillaries: bottom-up micro- and nanopatterning of functional materials on conductive substrates
A cost-effective and versatile methodology for bottom-up patterned growth of inorganic and metallic materials on the micro- and nanoscale is presented. Pulsed electrodeposition was employed to deposit arbitrary patterns of Ni, ZnO, and FeO(OH) of high quality, with lateral feature sizes down to 200–290 nm. The pattern was defined by an oxygen plasma-treated patterned PDMS mold in conformal contact with a conducting substrate and immersed in an electrolyte solution, so that the solid phases were deposited from the solution in the channels of the patterned mold. It is important that the distance between the entrance of the channels, and the location where deposition is needed, is kept limited. The as-formed patterns were characterized by high resolution scanning electron microscope, energy-dispersive X-ray analysis, atomic force microscopy, and X-ray diffraction
Desert algae - Soil crusts and diaphanous substrata as algal habitats
Desert algae development in soil crusts and diaphanous substrata as algal habitat
Curved planar quantum wires with Dirichlet and Neumann boundary conditions
We investigate the discrete spectrum of the Hamiltonian describing a quantum
particle living in the two-dimensional curved strip. We impose the Dirichlet
and Neumann boundary conditions on opposite sides of the strip. The existence
of the discrete eigenvalue below the essential spectrum threshold depends on
the sign of the total bending angle for the asymptotically straight strips.Comment: 7 page
Bifractality of the Devil's staircase appearing in the Burgers equation with Brownian initial velocity
It is shown that the inverse Lagrangian map for the solution of the Burgers
equation (in the inviscid limit) with Brownian initial velocity presents a
bifractality (phase transition) similar to that of the Devil's staircase for
the standard triadic Cantor set. Both heuristic and rigorous derivations are
given. It is explained why artifacts can easily mask this phenomenon in
numerical simulations.Comment: 12 pages, LaTe
High-precision measurement of the half-life of Ga
The beta-decay half-life of 62Ga has been studied with high precision using
on-line mass separated samples. The decay of 62Ga which is dominated by a 0+ to
0+ transition to the ground state of 62Zn yields a half-life of T_{1/2} =
116.19(4) ms. This result is more precise than any previous measurement by
about a factor of four or more. The present value is in agreement with older
literature values, but slightly disagrees with a recent measurement. We
determine an error weighted average value of all experimental half-lives of
116.18(4) ms.Comment: 9 pages, 5 figures, accepted for publication in PR
Rare events, escape rates and quasistationarity: some exact formulae
We present a common framework to study decay and exchanges rates in a wide
class of dynamical systems. Several applications, ranging form the metric
theory of continuons fractions and the Shannon capacity of contrained systems
to the decay rate of metastable states, are given
Electronic properties of buried hetero-interfaces of LaAlO3 on SrTiO3
We have made very thin films of LaAlO3 on TiO2 terminated SrTiO3 and have
measured the properties of the resulting interface in various ways. Transport
measurements show a maximum sheet carrier density of 1016 cm-2 and a mobility
around 104 cm2 V-1 s-1. In situ ultraviolet photoelectron spectroscopy (UPS)
indicates that for these samples a finite density of states exists at the Fermi
level. From the oxygen pressure dependence measured in both transport as well
as the UPS, we detail, as reported previously by us, that oxygen vacancies play
an important role in the creation of the charge carriers and that these
vacancies are introduced by the pulsed laser deposition process used to make
the heterointerfaces. Under the conditions studied the effect of LaAlO3 on the
carrier density is found to be minimal.Comment: 19 pages, 6 figure
Chaotic Cascades with Kolmogorov 1941 Scaling
We define a (chaotic) deterministic variant of random multiplicative cascade
models of turbulence. It preserves the hierarchical tree structure, thanks to
the addition of infinitesimal noise. The zero-noise limit can be handled by
Perron-Frobenius theory, just as the zero-diffusivity limit for the fast dynamo
problem. Random multiplicative models do not possess Kolmogorov 1941 (K41)
scaling because of a large-deviations effect. Our numerical studies indicate
that deterministic multiplicative models can be chaotic and still have exact
K41 scaling. A mechanism is suggested for avoiding large deviations, which is
present in maps with a neutrally unstable fixed point.Comment: 14 pages, plain LaTex, 6 figures available upon request as hard copy
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