Hydrogen tunneling in the perovskite ionic conductor BaCe(1-x)Y(x)O(3-d)

We present low-temperature anelastic and dielectric spectroscopy measurements on the perovskite ionic conductor BaCe(1-x)Y(x)O(3-x/2) in the protonated, deuterated and outgassed states. Three main relaxation processes are ascribed to proton migration, reorientation about an Y dopant and tunneling around a same O atom. An additional relaxation maximum appears only in the dielectric spectrum around 60 K, and does not involve H motion, but may be of electronic origin, e.g. small polaron hopping. The peak at the lowest temperature, assigned to H tunneling, has been fitted with a relaxation rate presenting crossovers from one-phonon transitions, nearly independent of temperature, to two-phonon processes, varying as T^7, to Arrhenius-like. Substituting H with D lowers the overall rate by 8 times. The corresponding peak in the dielectric loss has an intensity nearly 40 times smaller than expected from the classical reorientation of the electric dipole associated with the OH complex. This fact is discussed in terms of coherent tunneling states of H in a cubic and orthorhombically distorted lattice, possibly indicating that only H in the symmetric regions of twin boundaries exhibit tunneling, and in terms of reduction of the effective dipole due to lattice polarization.Comment: submitted to Phys. Rev.

Quantitative estimates of discrete harmonic measures

A theorem of Bourgain states that the harmonic measure for a domain in ℝ d is supported on a set of Hausdorff dimension strictly less thand [2]. We apply Bourgain's method to the discrete case, i.e., to the distribution of the first entrance point of a random walk into a subset of ℤ d ,d≥2. By refining the argument, we prove that for allβ>0 there existsρ(d,β)N(d,β), anyx ∈ ℤ d , and anyA ⊂ {1, ,n} d •{y∈ℤ whereν A,x (y) denotes the probability thaty is the first entrance point of the simple random walk starting atx intoA. Furthermore,ρ must converge tod asβ →

Methodology to compare costs of sanitation options for low-income peri-urban areas in Lusaka, Zambia

Urban slums and low-income peri-urban areas in developing countries are characterised by a lack of infrastructure. The absence of sustainable sanitation systems is one of the causes that can lead to a high level of water-borne diseases in these areas, especially during the rainy season. This paper presents a methodology for cost comparisons of sanitation system options with a focus on excreta management (a sanitation system consists of the household toilets, collection and transport of excreta, treatment and storage, and transport of sanitised excreta to reuse sites). Greywater collection and treatment are excluded from the analysis for simplicity reasons. We used three low-income peri-urban areas in Lusaka, Zambia, to demonstrate our proposed methodology. The population density in the three peri-urban areas ranges from 104 to 244 people/ha. Unlined pit latrines are the most common form of excreta management, even though drilled boreholes and shallow wells are used as sources for drinking water in the same areas. Based on four selection criteria (no use of water for transporting the waste, low costs, waste sanitisation, and no contribution to groundwater pollution from stored excreta), we have short-listed two options which meet most or all of the criteria: A conventional low-cost option (Option 5: VIP latrines with downstream processing) and an ecological sanitation option (Option 6: urine-diversion dehydrating (UDD) toilets with downstream processing). The concept designs for both options are based on the entire peri-urban population in Lusaka of approximately 1.23 m. people, and on the assumption that 12 residents who live on the same plot (or ‘compound’) would share one toilet. The paper details the assumptions used to create a set of default model input parameters which are used in the cost equations to calculate capital costs, annual operating costs and net present values (NVP). Based on this basic financial analysis, we calculated the following indicative costs: capital costs of 31 €/cap and 39 €/cap for Option 5 and Option 6, respectively. Annual operating costs per capita were estimated to be 2.3 €/a·cap and 2.1 €/a·cap) for Option 5 and Option 6, respectively. The NPV for Option 6 is about 14% higher than for Option 5 but the difference is not significant, given the accuracy of the cost estimate (about ± 25%). Overall, this paper shows that the two options are difficult to differentiate based on cost alone. The financial model allows examination of the relative contributions of the different components to the overall cost of the sanitation system. For example, the costs of urine storage and transport are significant contributors to the capital and operating costs of the Ecosan option, and ways to reduce these costs should be investigated.Keywords: NPV, millennium development goals, groundwater, ecological sanitation, Ecosan, VIP latrine, UDD toilet, financial model, reuse, excret

Brentano’s lectures on positivism (1893-1894) and his relationship to Ernst Mach

This paper is mainly about Brentano’s commentaries on Ernst Mach in his lectures “Contemporary philosophical questions” which he held one year before he left Austria. I will first identify the main sources of Brentano’s interests in Comte’s and J. S. Mill’s positivism during his Würzburg period. The second section provides a short overview of Brentano’s 1893-1894 lectures and his criticism of Comte, Kirchhoff, and Mill. The next sections bear on Brentano’s criticism of Mach’s monism and Brentano’s argument against the reduction of the mental based on his theory of intentionality. The last section is about Brentano’s proposal to replace the identity relation in Mach’s theory of elements by that of intentional correlation. I conclude with a remark on the history of philosophy in Austria

Nanoscale periodic domain patterns in tetragonal ferroelectrics: A phase-field study

Ferroelectrics form domain patterns that minimize their energy subject to imposed boundary conditions. In a linear, constrained theory, that neglects domain wall energy, periodic domain patterns in the form of multi-rank laminates can be identified as minimum-energy states. However, when these laminates (formed in a macroscopic crystal) comprise domains that are a few nanometers in size, the domain-wall energy becomes significant, and the behaviour of laminate patterns at this scale is not known. Here, a phase-field model, which accounts for gradient energy and strain energy contributions, is employed to explore the stability and evolution of the nanoscale multi-rank laminates. The stress, electric field, and domain wall energies in the laminates are computed. The effect of scaling is also discussed. In the absence of external loading, stripe domain patterns are found to be lower energy states than the more complex, multi-rank laminates, which mostly collapse into simpler patterns. However, complex laminates can be stabilized by imposing external loads such as electric field, average strain and polarization. The study provides insight into the domain patterns that may form on a macroscopic single crystal but comprising of nanoscale periodic patterns, and on the effect of external loads on these patterns.Comment: 13 pages, 14 figures, 2 table

Slip-controlled thin film dynamics

In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity. We study polymer films with thicknesses between 50 nm and 230 nm and various temperatures above the glass transition. We find slip lengths from 100 nm up to 1 micron on OTS and between 300 nm and 10 microns on DTS covered silicon wafers. The slip length decreases with temperature. The obtained values for the viscosity are consistent with independent measurements.Comment: 4 figure

Infrared radiometry experiment for Mariner Mars 1971

The infrared radiometer is designed to provide brightness temperatures of the surface of Mars by measuring the energy radiated in the 8 to 12 and 18 to 25 μ wavelength bands. The instrument is essentially the same as that flown on the Mariner Mars 1969 missions, modified only to define more sharply the field of view. Because Mariner Mars 1971 will orbit Mars, a given area of the planet will be observed at a variety of local times, and the characterization of the various areas by their thermophysical properties will be more complete than that obtained by Mariner Mars 1969

Quantitative estimates of discrete harmonic measures

A theorem of Bourgain states that the harmonic measure for a domain in $\R^d$ is supported on a set of Hausdorff dimension strictly less than $d$ \cite{Bourgain}. We apply Bourgain's method to the discrete case, i.e., to the distribution of the first entrance point of a random walk into a subset of $\Z ^d$, $d\geq 2$. By refining the argument, we prove that for all \b>0 there exists \rho (d,\b)N(d,\b), any $x \in \Z^d$, and any $A\subset \{1,..., n\}^d$ | \{y\in\Z^d\colon \nu_{A,x}(y) \geq n^{-\b} \}| \leq n^{\rho(d,\b)}, where $\nu_{A,x} (y)$ denotes the probability that $y$ is the first entrance point of the simple random walk starting at $x$ into $A$. Furthermore, $\rho$ must converge to $d$ as \b \to \infty.Comment: 16 pages, 2 figures. Part (B) of the theorem is ne

Mariner 1969 Infrared Radiometer Results: Temperatures and Thermal Properties of the Martian Surface

The reduced data of the Mariner 6 and 7 Infrared Radiometer Experiments are presented, along with a discussion of the reduction and calibration procedures. Evidence is presented showing that the surface of Mars is strongly nonhomogeneous in its thermal properties, on scales ranging from those of the classical light and dark areas to the limit of resolution of the radiometers. On the sunlit side, the mean thermal inertia, for admissible bolometric albedos, is 0.006 (cal cm^(-2) sec^(-1/2) °K^(-1)). The dark areas Syrtis Major and Mare Tyrrhenum, observed at night, require thermal inertias as high as 0.010. The temperatures measured over the circular basin Hellas require a bolometric albedo of 0.40 and also a high thermal inertia. The temperature measured over the south polar cap, 148° K, provides evidence that the major constituent of the frost deposit is CO_2