Measurement of kinematic and nuclear dependence of R = σ_L/σ_T in deep inelastic electron scattering

We report results on a precision measurement of the ratio R=σ_L/σ_T in deep inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤10 (GeV/c)^2. Our results show, for the first time, a clear falloff of R with increasing Q^2. Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included. At small x, the data on R favor structure functions with a large gluon contribution. We also report results on the differences R_A-R_D and the cross section ratio σ^A/σ^D between Fe and Au nuclei and the deuteron. Our results for R_A-R_D are consistent with zero for all x, Q^2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The ratios σ^A/σ^D from all recent experiments, at all x, Q^2 values, are now in agreement

Measurement of the Difference in R=σ_L/σ_T and of σ^A/σ^D in Deep-Inelastic e-D, e-Fe, and e-Au Scattering

We measured the differences in R=σ_L/σ_T and the cross-section ratio σA/σD in deep-inelastic electron scattering from D, Fe, and Au nuclei in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤5 (Gev/c)^2. Our results for R^A-R^D are consistent with zero for all x and Q^2, indicating that possible contributions to R from nuclear higher-twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The European Muon Collaboration effect is reconfirmed, and the low-x data from all recent experiments, at all Q^2, are now in agreement

Longitudinal and Transverse Response Functions in ^(56)Fe(e,e') at Momentum Transfer near 1 GeV/c

Inclusive electron-scattering cross sections have been measured for ^(56)Fe in the quasielastic region at electron energies between 0.9 and 4.3 GeV, at scattering angles of 15° and 85°. Longitudinal and transverse response functions at a q of 1.14 GeV/c have been extracted using a Rosenbluth separation. The experimental Coulomb sum has been obtained with aid of an extrapolation. The longitudinal response function, after correction for Coulomb distortion, is lower than quasifree-scattering-model predictions at the quasielastic peak and on the high-ω side

Combined U–Th/He and 40Ar/39Ar geochronology of post-shield lavas from the Mauna Kea and Kohala volcanoes, Hawaii

Late Quaternary, post-shield lavas from the Mauna Kea and Kohala volcanoes on the Big Island of Hawaii have been dated using the 40Ar/39Ar and U–Th/He methods. The objective of the study is to compare the recently demonstrated U–Th/He age method, which uses basaltic olivine phenocrysts, with 40Ar/39Ar ages measured on groundmass from the same samples. As a corollary, the age data also increase the precision of the chronology of volcanism on the Big Island. For the U–Th/He ages, U, Th and He concentrations and isotopes were measured to account for U-series disequilibrium and initial He. Single analyses U–Th/He ages for Hamakua lavas from Mauna Kea are 87 ± 40 to 119 ± 23 ka (2σ uncertainties), which are in general equal to or younger than 40Ar/39Ar ages. Basalt from the Polulu sequence on Kohala gives a U–Th/He age of 354 ± 54 ka and a 40Ar/39Ar age of 450 ± 40 ka. All of the U–Th/He ages, and all but one spurious 40Ar/39Ar ages conform to the previously proposed stratigraphy and published 14C and K–Ar ages.The ages also compare favorably to U–Th whole rock–olivine ages calculated from 238U–230Th disequilibria. The U–Th/He and 40Ar/39Ar results agree best where there is a relatively large amount of radiogenic 40Ar (>10%), and where the 40Ar/36Ar intercept calculated from the Ar isochron diagram is close to the atmospheric value. In two cases, it is not clear why U–Th/He and 40Ar/39Ar ages do not agree within uncertainty. U–Th/He and 40Ar/39Ar results diverge the most on a low-K transitional tholeiitic basalt with abundant olivine. For the most alkalic basalts with negligible olivine phenocrysts, U–Th/He ages were unattainable while 40Ar/39Ar results provide good precision even on ages as low as 19 ± 4 ka. Hence, the strengths and weaknesses of the U–Th/He and 40Ar/39Ar methods are complimentary for basalts with ages of order 100–500 ka

Atomic Scale Depth Profile of Space Weathering in an Itokawa Olivine Grain

No abstract available

Tunable Single-Walled Carbon Nanotube Fluorescence Emission Via Associated DNA Sequence

Single‑walled carbon nanotubes, or SWCNTs, are nanomaterials that possess unique characteristics, most importantly their differing structural arrangement in terms of chirality. Each single‑walled carbon nanotube exhibits a unique fluorescence spectra that is dependent upon its chirality. The association of single‑stranded DNA (ssDNA) with SWCNTs is monitored by near‑infrared fluorescence spectroscopy. The DNA:SWCNT hybrid exhibits fluorescence spectra dependence upon both the selected sequence and the selected chirality

Print-production education for graphic designers

Institutions teaching graphic design often emphasize concepts and methods of practice that yield excellent design abilities. Too often, however, the teaching of the methods in which those designs are then printed and produced are considered secondary due to a variety of reasons including cost considerations, available technology, and time available within an existing curriculum to teach such topics. Throughout history, changes in printing technology have changed the way designers\u27 work is produced. What was once a series of steps involving a multitude of professionals able to fill the design-to-print transition is now often directly in the hands of the designer. In essence, digital printing technology has led the designer to become the typesetter, prepress operator, and even the printer. It is important that graphic designers are able to understand the ways in which their work is printed and produced to allow them to take advantage of the variations and possibilities inherent in each of the different printing and output devices. Lack of communication between designer and printer often leads to less than desirable printed pieces. A lecture course on print production may explain the topics, but fails to give students a hands-on experience in the craft of printing in a manner comparable to the rest of their studio-based education. This study considers the limitations of print-production education at graphic design institutions and considers how print-production methods and techniques can be taught using a variety of teaching and evaluation methods, and how those methods can be better integrated into the curricula at graphic design institutions. In particular, the study will look at what knowledge is necessary in a course on print production and attempt to validate the importance of that knowledge. It will also evaluate existing resources on the topic. Additional consideration is given to those subjects within the field students and printing professionals consider common sources of errors. Through the identification of important knowledge areas, resources, and problematic topics, a proposal will be made in an attempt to strengthen print-production education for graphic design students