Properties of lift-off structured high Tc microbridges

Microbridges and DC SQUIDs (superconducting quantum interference devices) were fabricated, using a lift-off technique, from RF sputtered YBaCuO films on MgO single-crystal substrates. Microwave measurements at 9 GHz on microbridges and the magnetic-field dependence of their critical current reveal wide bridge behaviour up to temperatures near the maximum operating temperature of the bridge. Mostly, a linear dependence of the critical current on the temperature is found, which is connected with high intrinsic 1/f noise if the bridge is constant-current-biased slightly above the critical current. In some bridges and DC SQUIDs, regimes with a temperature dependence proportional to (1-T/Tc)1.5 are found. In this case the 1/f noise level is much smaller and SQUID modulation can be followed to about 65

Solving the characteristic initial value problem for colliding plane gravitational and electromagnetic waves

A method is presented for solving the characteristic initial value problem for the collision and subsequent nonlinear interaction of plane gravitational or gravitational and electromagnetic waves in a Minkowski background. This method generalizes the monodromy transform approach to fields with nonanalytic behaviour on the characteristics inherent to waves with distinct wave fronts. The crux of the method is in a reformulation of the main nonlinear symmetry reduced field equations as linear integral equations whose solutions are determined by generalized (``dynamical'') monodromy data which evolve from data specified on the initial characteristics (the wavefronts).Comment: 4 pages, RevTe

Collision of plane gravitational and electromagnetic waves in a Minkowski background: solution of the characteristic initial value problem

We consider the collisions of plane gravitational and electromagnetic waves with distinct wavefronts and of arbitrary polarizations in a Minkowski background. We first present a new, completely geometric formulation of the characteristic initial value problem for solutions in the wave interaction region for which initial data are those associated with the approaching waves. We present also a general approach to the solution of this problem which enables us in principle to construct solutions in terms of the specified initial data. This is achieved by re-formulating the nonlinear dynamical equations for waves in terms of an associated linear problem on the spectral plane. A system of linear integral ``evolution'' equations which solve this spectral problem for specified initial data is constructed. It is then demonstrated explicitly how various colliding plane wave space-times can be constructed from given characteristic initial data.Comment: 33 pages, 3 figures, LaTeX. Accepted for publication in Classical and Quantum Gravit

ARXPS-studies ofcˆ-axis textured YBa2Cu3Ox-films

YBa2Cu3Ox sputter deposited cold on MgO grows in O2 annealing epitaxially to a transparent, superconducting film with Tc 80K. The unscraped surfaces of these films are smooth showing XPS lines changing with photoelectron take-off angle. This enhanced data base allows to separate the different chemical compounds (hydroxide, peroxide, carbonate, carboxyle, cuprate, graphite ...) and to obtain their spatial distribution. This yields the compounds, their amount and distribution making up the cinder growing with O2-anneal at internal and external surfaces. The cinder stoichiometry gives insights in the chemistry going on in O2 annealing. Below the cinder the signature ofcˆ-axis oriented YBa2Cu3Ox is identified, showing that a Ba-oxide layer forms the stable surface. This coats insulating CuO2 and Y-oxide layers yielding so an intrinsic dead layer

Studies on the market milk of Iowa

A study of market milk conditions in Iowa by the market milk laboratory of the dairy department at Iowa State College reveals the fact that the state has a real milk problem to deal with. In the cities and towns in which the investigation was carried on, the results indicate these facts: The milk and cream, whether raw or pasteurized, commonly contains excessive numbers of bacteria, altho samples without excessive numbers were sometimes found. The presence of large numbers of bacteria in pasteurized milk and cream indicates that the heat exposure used in some plants is too low, altho improper handling after pasteurization is also partly responsible for this condition

Fermented Milk

The consumption of various types of fermented milk is common in all countries in which milk is available. The food value of such products is unquestioned and their desirability, especially in the case of certain intestinal disorders, is insisted on by many persons. The recent necessity for food conservation has emphasized the possibility of preparing nourishing beverages as well as liquids to be used in cookery from skim milk, buttermilk and whey, which would otherwise be discarded or used for animal feeding

The pasteurization of milk in the final package

In the work reported in this bulletin an effort was made to determine the most favorable vat temperature and time of exposure for final package pasteurization. The only type of cap used was the Dacro cap, although; probably in a general way the results would be applicable also to other packages used for pasteurizing. The points considered in the determination were bacterial efficiency, creaming ability and the heated flavor produced. High pasteurization temperatures are undesirable because of the reduced creaming ability and marked heated flavor of milk so treated