Aerodynamic data on a large semispan tilting wing with 0.5-diameter chord, double-slotted flap, and both left-hand and right-hand rotation of a single propeller

Longitudinal aerodynamic data on large-scale semispan V/STOL tilt-wing configuration having single propeller with left and right hand rotatio

Solution to the twin image problem in holography

While the invention of holography by Dennis Gabor truly constitutes an ingenious concept, it has ever since been troubled by the so called twin image problem limiting the information that can be obtained from a holographic record. Due to symmetry reasons there are always two images appearing in the reconstruction process. Thus, the reconstructed object is obscured by its unwanted out of focus twin image. Especially for emission electron as well as for x- and gamma-ray holography, where the source-object distances are small, the reconstructed images of atoms are very close to their twin images from which they can hardly be distinguished. In some particular instances only, experimental efforts could remove the twin images. More recently, numerical methods to diminish the effect of the twin image have been proposed but are limited to purely absorbing objects failing to account for phase shifts caused by the object. Here we show a universal method to reconstruct a hologram completely free of twin images disturbance while no assumptions about the object need to be imposed. Both, amplitude and true phase distributions are retrieved without distortion

Comment on Neutron-Proton Spin-Correlation Parameter A_{ZZ} at 68 Mev

We present two arguments indicating that the large value for the $\epsilon_1$ mixing parameter at 50 MeV, which the Basel group extracted from their recent $A_{zz}$ measurement, may be incorrect. First, there are nucleon-nucleon (NN) potentials which predict the $\epsilon_1$ at 50 MeV substantially below the Basel value and reproduce the Basel $A_{zz}$ data accurately. Second, the large value for $\epsilon_1$ at 50 MeV proposed by the Basel group can only be explained by a model for the NN interaction which is very unrealistic (no $\rho$-meson and essentially a point-like $\pi NN$ vertex) and overpredicts the $\epsilon_1$ in the energy range where it is well determined (150--500 MeV) by a factor of two.Comment: 6 pages text (LaTex) and 2 figures (paper, will be faxed upon request), UI-NTH-930

The health of the poor: Women living in informal settlements

Objectives: A large share of the urban population in developing countries lives in informal settlements or “slums” today. This study investigates the association between slum residence and health among adult Ghanaian women residing in the Accra Metropolitan Area.Methods: Health data collected as part of the Women’s Health Study of Accra round II (WHSA-II) was combined with data from the Household and Welfare Study of Accra (HAWS) to compare the health of female slum dwellers to the health of female non-slum dwellers living in the Accra Metropolitan Area. Group means were calculated and multivariate linear regression models were estimated to compare eight domains ofhealth as measured by the short-form 36 (SF-36) questionnaire.Results: Women living in informal settlements were found to display consistently better health. Conditional on all observable characteristics, women living in informal settlements scored higher on all self-reportedhealth outcomes than women living in non-slum areas. The differences appear largest for general health as well as for the physical role functioning domains, and appear smallest for the social role functioning and bodily pain domains.Conclusions: The results presented suggest that slum residence does not have a negative effect on self-reported health among women in Accra. Three factors may contribute to the generally positive association betweenslum residence and observed outcomes: i) selfselection of individuals with strong health into informal settlements and an accordingly small impact ofenvironmental factors on health ii) self-selection of more driven and ambitious individuals into slum neighborhoods who may have a generally more positive view of their health and iii) the geographic placement ofslum neighborhoods in central neighborhoods with relatively easy access to health facilities

Exceptional type-I superconductivity of the layered silver oxide Ag5_5Pb2_2O6_6

We report zero-resistivity transition and the details of magnetic transition of a layered silver oxide Ag$_5$Pb$_2$O$_6$ single crystal, which make definitive evidence of superconductivity in this compound. In the AC susceptibility of a mono-crystal, we observed large supercooling, as well as positive peaks in the real part of the susceptibility indicating the reversibility of magnetic process. These observations reveal that Ag$_5$Pb$_2$O$_6$ is probably the first oxide that shows type-I superconductivity. Evaluation of the superconducting parameters not only gives confirming evidence of type-I superconductivity, but also indicates that it is a dirty-limit superconductor. We also analyze supercooling to determine the upper limit of the Ginzburg-Landau parameter.Comment: v2: PACS numbers are adde

Kinetic oscillations in the NO + CO reaction on Pt(100): Experiments and mathematical modeling

The reaction of NO and CO on Pt(100) exhibits two branches of steady state production of N2 and CO2 and the occurrence of kinetic oscillations. This system was studied under steady flow conditions in the 10−6mbar total pressure range using low‐energy electron diffraction‐(LEED), work function measurement, and mass spectrometry for determination of the reaction rate. These studies revealed that kinetic oscillations can only be initiated from one of the two stable reaction branches. Two separate existence regions were detected in which the oscillations are always damped. Oscillations can be very reproducibly excited by slight decreases in temperature. The 1×1 hex phase transition of the surface structure was observed to take place only in one of the two regions of reaction rate oscillations. Its influence seems to be of minor relevance to the mechanism of oscillations as oscillations in one region occur on the surface that maintains a 1×1 structure. The experiments were modeled by a set of coupled differential equations based on knowledge about the elementary reaction steps. The model calculations reproduced the steady states of the reaction as well as the occurrence of kinetic oscillations in different ranges in excellent agreement with experimental observation. In the model, the phase transition also has no relevance for the oscillation mechanism. The occurrence of oscillations can be rationalized in terms of a periodic sequence of autocatalytic ‘‘surface explosions’’ and the restoration of an adsorbate‐covered surface. The damping, experimentally observed, is attributed to insufficient spatial coupling between different regions of the surface

Precise Null Pointer Analysis Through Global Value Numbering

Precise analysis of pointer information plays an important role in many static analysis techniques and tools today. The precision, however, must be balanced against the scalability of the analysis. This paper focusses on improving the precision of standard context and flow insensitive alias analysis algorithms at a low scalability cost. In particular, we present a semantics-preserving program transformation that drastically improves the precision of existing analyses when deciding if a pointer can alias NULL. Our program transformation is based on Global Value Numbering, a scheme inspired from compiler optimizations literature. It allows even a flow-insensitive analysis to make use of branch conditions such as checking if a pointer is NULL and gain precision. We perform experiments on real-world code to measure the overhead in performing the transformation and the improvement in the precision of the analysis. We show that the precision improves from 86.56% to 98.05%, while the overhead is insignificant.Comment: 17 pages, 1 section in Appendi