The corrosion mechanisms for primer coated 2219-T87 aluminum

To investigate metal surface corrosion and the breakdown of metal protective coatings, the ac Impedance Method was applied to zinc chromate primer coated 2219-T87 aluminum. The EG&GPARC Model 368 ac Impedance Measurement System, along with dc measurements with the same system using the Polarization Resistance Method, was used to monitor changing properties of coated aluminum disks immersed in 3.5 percent NaCl solutions buffered at pH 5.5 and pH 8.2 over periods of 40 days each. The corrosion system can be represented by an electronic analog called an equivalent circuit consisting of resistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for resistances and capacitances, that can be assigned in the equivalent circuit following a least squares analysis of the data, describe changes occurring on the corroding metal surface and in the protective coatings. A suitable equivalent circuit has been determined which predicts the correct Bode phase and magnitude for the experimental sample. The dc corrosion current density data are related to equivalent circuit element parameters

The Effectiveness of Suggestopedia Method with Wordwall Picture in Increasing Vocabulary Mastery with Learning Disabilities

This study investigates the effects of Suggestopedia method with wordwall picture in increase the vocabulary mastery students of SMPLB Negeri Parepare in academic year 2016/ 2017. This method engages the students’ attentions and various fun learning activities which decreased the students’ boredom during their learning. Wordwall picture provides the students’ illustrations and ideas in their minds. It applied mixed methods research design quantitative and qualitative approaches with single group interrupted time-series design. The population are who students with learning disabilities of SMPLB Parepare in academic year 2016/2017 which consist of 11 students and the sample constitútes consist of 5 students.  This research  used sampling as  a technique of sampling. Based on the quantitative analysis, the result showed that 1) student test were significant accorbing to the questionnaire, the result show thet the students motivation incresed. It means that suggestopedia method with wordwall picture affected the students vocebulary mastery in learning. The result also proved that students interest in learning english has a significant relationship or influence with students vocebulary score. 2) The qualitative data from questionnaire showed that students’ motivation increased. It means that Suggestopedia method with wordwall picture affected the students vocabulary, mastery in learning, it proved that Suggestopedia Method with Wordwall Picture able to increase the interest in learning English of the students with disabilities learning of SMPLB Parepare

Prader-Willi syndrome: are there population differences?

A 15 1/2-year-old black female with features consistent with the Prader-Willi syndrome is reported. This is the second case report of a black individual and the first case of a black female with the Prader-Willi syndrome. There is an apparent paucity of blacks reported with this condition. Whether this difference is a true difference or represents under-reporting is not known. We urge reporting of individuals representing other racial groups with this disorder and suggest population studies to determine the incidence as well as the true population difference in the Prader-Willi syndrome

On the voting power of an alliance and the subsequent power of its members

Even, and in fact chiefly, if two or more players in a voting game have on a binary issue independent opinions, they may have interest to form a single voting alliance giving an average gain of influence for all of them. Here, assuming the usual independence of votes, we first study the alliance voting power and obtain new results in the so-called asymptotic limit for which the number of players is large enough and the alliance weight remains a small fraction of the total of the weights. Then, we propose to replace the voting game inside the alliance by a random game which allows new possibilities. The validity of the asymptotic limit and the possibility of new alliances are examined by considering the decision process in the Council of Ministers of the European Union.

Study of ISM tracers in galaxies

We collected data for two samples of normal and interacting galaxies for a total of 2953 galaxies having fluxes in one or more of the following wavebands: FIR, 21 cm line, CO(1-0) lines and soft X-ray. The large set of data obtained allowed us to revisit some of the already known relations between the different tracers of the interstellar medium (ISM), such as the link between the FIR flux and the CO line emission, the relation between X-ray emission and the blue or FIR luminosity. The relation lacking from observations for early-type galaxies has been discussed and explained in detail in the frame of a suitable theoretical model, obtained by coupling chemo-dynamical N-body simulations with a dusty spectrophotometric code of population synthesis.Comment: 2 pages, o appear in the Proceedings of the Conf. "From Stars to Galaxies: Building the Pieces to Build Up the Universe", Vallenari et al. eds., ASP Conf. Serie

Woody Vegetation in the Upland Region of Rarotonga, Cook Islands

Rarotonga is the largest (64 km2 ) and by far the highest (652 m) of the Cook Islands. The native coastal and lowland vegetation of this high volcanic, tropical island has been either completely removed or heavily disturbed. Numerous exotic plant species have been introduced and many of these are now naturalized in the lower elevation habitats of the island. The results of this initial, quantitative study in the upland forests of Rarotonga indicate, however, that the plant life of the rugged interior is still largely dominated by native species. Over 92 percent of all the woody plants (dbh > 2.5 cm) sampled in the 19 upland forest transects are either indigenous or endemic to Rarotonga. Native plants also accounted for more than 95 percent of the basal area covered by the woody vegetation in the upland study area. Three basic native plant associations have been recognized by dendrogram analysis: (1) the Homalium montane forest; (2) the Fagraea-Fitchia ridge forest; and (3) the Metrosideros cloud forest. The first two associations develop under subtropical climatic conditions, while the cloud forest is adapted to warm temperate conditions. Some aspects of the biogeographical significance of this unique forest region and the ecological implications of human disturbance in the uplands are also discussed

Magnon squeezing in an antiferromagnet: reducing the spin noise below the standard quantum limit

At absolute zero temperature, thermal noise vanishes when a physical system is in its ground state, but quantum noise remains as a fundamental limit to the accuracy of experimental measurements. Such a limitation, however, can be mitigated by the formation of squeezed states. Quantum mechanically, a squeezed state is a time-varying superposition of states for which the noise of a particular observable is reduced below that of the ground state at certain times. Quantum squeezing has been achieved for a variety of systems, including the electromagnetic field, atomic vibrations in solids and molecules, and atomic spins, but not so far for magnetic systems. Here we report on an experimental demonstration of spin wave (i.e., magnon) squeezing. Our method uses femtosecond optical pulses to generate correlations involving pairs of magnons in an antiferromagnetic insulator, MnF2. These correlations lead to quantum squeezing in which the fluctuations of the magnetization of a crystallographic unit cell vary periodically in time and are reduced below that of the ground state quantum noise. The mechanism responsible for this squeezing is stimulated second order Raman scattering by magnon pairs. Such squeezed states have important ramifications in the emerging fields of spintronics and quantum computing involving magnetic spin states or the spin-orbit coupling mechanism