38,551 research outputs found
Voting on the choice of core languages in the European Union
This is the post-print version of the final paper published in European Journal of Political Economy. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2008 Elsevier B.V.Extensive multilingualism is one of the most important and fundamental principles of the European Union (EU). However, a large number of languages (currently 23) hinders communication and imposes substantial financial and legal costs. On the other hand, the reduction of the number of languages would disenfranchise some or many EU citizens. We use the results of a survey on languages and argue that even though a linguistic reform reducing the number of languages is unlikely to gain sufficient political support today, this may change in the future since young people are more proficient at speaking foreign languages
Lunar Surface Gravimeter Experiment
The lunar surface gravimeter which was emplaced on the moon by the Apollo 17 flight is described and a schematic diagram of the sensor is provided. The objective of the lunar surface gravimeter is to use the moon as an instrumented antenna to detect gravitational waves. Another objective is to measure tidal deformation of the moon. Samples of signals received during lunar sunrise activity and during quiet periods are presented in graph form based on power spectrum analysi
Applications of luminescence techniques to the study of the lunar surface
Optical fluorescence spectra of rock-forming minerals for identifying mineral grains found on lunar surfac
Multiferroicity and colossal magneto-capacitance in Cr-thiospinels
The sulfur based Cr-spinels RCr2S4 with R = Cd and Hg exhibit the coexistence
of ferromagnetic and ferroelectric properties together with a pronounced
magnetocapacitive coupling. While in CdCr2S4 purely ferromagnetic order is
established, in HgCr2S4 a bond-frustrated magnetic ground state is realized,
which, however, easily can be driven towards a ferromagnetic configuration in
weak magnetic fields. This paper shall review our recent investigation for both
compounds. Besides the characterization of the magnetic properties, the complex
dielectric permittivity was studied by means of broadband dielectric
spectroscopy as well as measurements of polarization hysteresis and
pyro-currents. The observed colossal magneto-capacitive effect at the magnetic
transition seems to be driven by an enormous variation of the relaxation
dynamics.Comment: 10 pages, 11 figure
Multiferroic behavior in CdCr2X4 (X = S, Se)
The recently discovered multiferroic material CdCr2S4 shows a coexistence of
ferromagnetism and relaxor ferroelectricity together with a colossal
magnetocapacitive effect. The complex dielectric permittivity of this compound
and of the structurally related CdCr2Se4 was studied by means of broadband
dielectric spectroscopy using different electrode materials. The observed
magnetocapacitive coupling at the magnetic transition is driven by enormous
changes of the relaxation dynamics induced by the development of magnetic
order
Retention of Low Income Children in Three Dental Studies Investigating Early Childhood Caries
Background: To our knowledge no dental studies have looked closely at subject retention, which is crucial to better understand oral health disparities. In this paper, we report retention rates and review and attempt to assess which retention strategies utilized in 3 dental research studies investigating ECC were effective for retaining WIC-enrolled children. The purpose of this paper is to discuss challenges that were encountered when working with these populations, describe characteristics of those not retained, and summarize some recommendations for future dental studies working at WIC sites. Methods: Three dental studies were conducted at WIC clinics in Iowa. Retention strategies focused on maintenance of contact over time, persistence in rescheduling appointments, utilization of incentives, high recruitment, and frequent communication with parents and program staff. Results: Retention rates in the studies ranged from 60 to 75 percent at the final research interventions. Studies were challenged by frequent moves of subjects, missed appointments, disconnected phones, busy schedules of parents, transportation problems, loss of child custody, family illness, and lack of interest. Those not retained in the studies were more likely to be younger, single, and less educated, with a lower household income and a non-Caucasian child. Lower retention was also associated with the presence of carious lesions. Conclusions: Despite many challenges, studies had good retention rates and benefited from the retention strategies. Future dental studies at WIC clinics may also benefit from arranging transportation, obtaining a free, 800 callback number, and offering after-hours appointments for working parents
Laboratory studies, analysis, and interpretation of the spectra of hydrocarbons present in planetary atmospheres including cyanoacetylene, acetylene, propane, and ethane
Combining broadband Fourier transform spectrometers (FTS) from the McMath facility at NSO and from NRC in Ottawa and narrow band TDL data from the laboratories with computational physics techniques has produced a broad range of results for the study of planetary atmospheres. Motivation for the effort flows from the Voyager/IRIS observations and the needs of Voyager analysis for laboratory results. In addition, anticipation of the Cassini mission adds incentive to pursue studies of observed and potentially observable constituents of planetary atmospheres. Current studies include cyanoacetylene, acetylene, propane, and ethane. Particular attention is devoted to cyanoacetylen (H3CN) which is observed in the atmosphere of Titan. The results of a high resolution infrared laboratory study of the line positions of the 663, 449, and 22.5/cm fundamental bands are presented. Line position, reproducible to better than 5 MHz for the first two bands, are available for infrared astrophysical searches. Intensity and broadening studies are in progress. Acetylene is a nearly ubiquitous atmospheric constituent of the outer planets and Titan due to the nature of methane photochemistry. Results of ambient temperature absolute intensity measurements are presented for the fundamental and two two-quantum hotband in the 730/cm region. Low temperature hotband intensity and linewidth measurements are planned
Colossal magnetocapacitance and colossal magnetoresistance in HgCr2S4
We present a detailed study of the dielectric and charge transport properties
of the antiferromagnetic cubic spinel HgCr2S4. Similar to the findings in
ferromagnetic CdCr2S4, the dielectric constant of HgCr2S4 becomes strongly
enhanced in the region below 60 - 80 K, which can be ascribed to polar
relaxational dynamics triggered by the onset of ferromagnetic correlations. In
addition, the observation of polarization hysteresis curves indicates the
development of ferroelectric order below about 70 K. Moreover, our
investigations in external magnetic fields up to 5 T reveal the simultaneous
occurrence of magnetocapacitance and magnetoresistance of truly colossal
magnitudes in this material.Comment: 4 pages, 4 figure
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