Proof of a generalized Geroch conjecture for the hyperbolic Ernst equation

We enunciate and prove here a generalization of Geroch's famous conjecture concerning analytic solutions of the elliptic Ernst equation. Our generalization is stated for solutions of the hyperbolic Ernst equation that are not necessarily analytic, although it can be formulated also for solutions of the elliptic Ernst equation that are nowhere axis-accessible.Comment: 75 pages (plus optional table of contents). Sign errors in elliptic case equations (1A.13), (1A.15) and (1A.25) are corrected. Not relevant to proof contained in pape

Carbon nanotubes immersed in superfluid helium: the Impact of quantum confinement on wetting and capillary action

7 págs.; 5 figs.; 1 tab. ; Associated content mp4 video: http://pubs.acs.org/doi/suppl/10.1021/acs.jpclett.6b02414A recent experimental study [Ohba, Sci. Rep. 2016, 6, 28992] of gas adsorption on single-walled carbon nanotubes at temperatures between 2 and 5 K reported a quenched propagation of helium through carbon nanotubes with diameters below 7 Å despite the small kinetic diameter of helium atoms. After assessing the performance of a potential model for the He−nanotube interaction via ab initio calculations with density functional theorybased symmetry adapted perturbation theory, we apply orbital-free helium density functional theory to show that the counterintuitive experimental result is a consequence of the exceptionally high zeropoint energy of helium and its tendency to form spatially separated layers of helium upon adsorption at the lowest temperatures. Helium filling factors are derived for a series of carbon nanotubes and compared to the available experimental data. © 2016 American Chemical SocietyThis work has been supported by the COST Action CM1405 “Molecules in Motion (MOLIM)”. M.P.d.L.-C. gratefully acknowledges support from MINECO (Spain) under Grant MAT2016-75354-P and thanks the CTI (CSIC) and CESGA supercomputer facilities (Spain) for the resources provided.Peer reviewe

Monodromy-data parameterization of spaces of local solutions of integrable reductions of Einstein's field equations

For the fields depending on two of the four space-time coordinates only, the spaces of local solutions of various integrable reductions of Einstein's field equations are shown to be the subspaces of the spaces of local solutions of the ``null-curvature'' equations constricted by a requirement of a universal (i.e. solution independent) structures of the canonical Jordan forms of the unknown matrix variables. These spaces of solutions of the ``null-curvature'' equations can be parametrized by a finite sets of free functional parameters -- arbitrary holomorphic (in some local domains) functions of the spectral parameter which can be interpreted as the monodromy data on the spectral plane of the fundamental solutions of associated linear systems. Direct and inverse problems of such mapping (``monodromy transform''), i.e. the problem of finding of the monodromy data for any local solution of the ``null-curvature'' equations with given canonical forms, as well as the existence and uniqueness of such solution for arbitrarily chosen monodromy data are shown to be solvable unambiguously. The linear singular integral equations solving the inverse problems and the explicit forms of the monodromy data corresponding to the spaces of solutions of the symmetry reduced Einstein's field equations are derived.Comment: LaTeX, 33 pages, 1 figure. Typos, language and reference correction

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

Iowa Educational Market Milk Contest

According to the United States Department of Agriculture, the firnt milk and cream contest In this country was held at the National Dairy Show at Chicago In 1906. Since that time such contests have been held in conjunction with various dairy shows, fairs and other meetings, such as campaigns for the improvement of city milk supplies, In which milk producers and dealers were Interested; up to February, 1915, 87 such contests had been judged by members of the Dairy division or the United States Department or Agriculture. In general, it is believed that these contests have been of distinct service from an educational standpoint In teaching exhibitors the ad· vantages or disadvantages of various methods of handling milk, altho It Is recognized that commonly the attention given to the exhibited milk or cream is not given to the general supply. The Dairy department of Iowa State college held its first educational market milk contest December 2.J, 1914, in connection with Its annual short course. Previous studies had shown that much of the milk (both raw and pasteurized) sold In the state was not of the quality it should be and the contest was proposed as a means of stimulating its Improvement

Studies on the clarification of milk—II

In a former publication of this station the results obtained in a study of the clarification of milk with the DeLaval clarifier are presented. The data show: first that commonly, altho by no means constantly, the plates poured from clarified milk contained a larger number of colonies than plates poured from Unclarified milk of the same lot; this was undoubtedly due to a breaking up of the clumps of organisms and should be spoken of as an \u27apparent increase since the large number of bacteria in the slime indicates that there was actually an elimination of organisms; second, that there was in every case a decrease in the number of cells during clarification; third, that the clarifier slime contained a large number of bacteria and cells in addition to a variable amount of dirt and sometimes red blood cells. The publication pointed out that, while it must \u27be admitted it would be desirable to prevent foreign material from getting into milk, this is impossible for the great bulk of our milk supply because of the increased cost of production and that accordingly clarification of milk followed by efficient pasteurization must be looked upon as a commendable substitution

Observables for spacetimes with two Killing field symmetries

The Einstein equations for spacetimes with two commuting spacelike Killing field symmetries are studied from a Hamiltonian point of view. The complexified Ashtekar canonical variables are used, and the symmetry reduction is performed directly in the Hamiltonian theory. The reduced system corresponds to the field equations of the SL(2,R) chiral model with additional constraints. On the classical phase space, a method of obtaining an infinite number of constants of the motion, or observables, is given. The procedure involves writing the Hamiltonian evolution equations as a single `zero curvature' equation, and then employing techniques used in the study of two dimensional integrable models. Two infinite sets of observables are obtained explicitly as functionals of the phase space variables. One set carries sl(2,R) Lie algebra indices and forms an infinite dimensional Poisson algebra, while the other is formed from traces of SL(2,R) holonomies that commute with one another. The restriction of the (complex) observables to the Euclidean and Lorentzian sectors is discussed. It is also shown that the sl(2,R) observables can be associated with a solution generating technique which is linked to that given by Geroch.Comment: 23 pages (LateX-RevTeX), Alberta-Thy-55-9

Growth control of GaAs nanowires using pulsed laser deposition with arsenic over pressure

Using pulsed laser ablation with arsenic over pressure, the growth conditions for GaAs nanowires have been systematically investigated and optimized. Arsenic over pressure with As$_2$ molecules was introduced to the system by thermal decomposition of polycrystalline GaAs to control the stoichiometry and shape of the nanowires during growth. GaAs nanowires exhibit a variety of geometries under varying arsenic over pressure, which can be understood by different growth processes via vapor-liquid-solid mechanism. Single-crystal GaAs nanowires with uniform diameter, lengths over 20 $\mu$m, and thin surface oxide layer were obtained and can potentially be used for further electronic characterization