Conductivity phenomena in polycrystalline zinc oxide films

Photoconductivity and electric conductivity of polycrystalline zinc oxide thin film under low intensity irradiatio

Three Decades of Reliability in Communication Content Analyses: Reporting of Reliability Statistics and Coefficient Levels in Three Top Journals

This study examines reliability reporting in content analysis articles ( N = 672) in three flagship communication journals. Data from 1985 to 2014 suggest improvements in reporting across time and also identify areas for additional improvement. Data show increased reporting of chance-corrected reliability coefficients and reporting reliability for all study variables, although increases were inconsistent among journals and the most recent time period showed slight declines. In general, the most often used coefficient was Scott’s Pi; however, Krippendorff’s Alpha was most used in the latest study period. Reporting of low reliability coefficients increased but then decreased most recently. Implications and areas for improvement are discussed

Assessing the Reporting of Reliability in Published Content Analyses: 1985–2010

Content analysis is a common research method employed in communication studies. An important part of content analysis is establishing the reliability of the coding protocol, and reporting must be detailed enough to allow for replication of methodological procedures. This study employed a content analysis of published content analysis articles (N=581) in three communication journals over a 26-year period to examine changes in reliability sampling procedures and reporting of reliability coefficients across time. Findings indicate that general improvements have been made in the detail of reporting reliability, in the practice of reporting reliability coefficients that take chance into consideration, and in the reporting of reliability coefficients for more than one variable. However, explaining the reliability sampling process and use of a probability or census reliability sample did not change over time. In recent years, the preponderance of articles did not explain the reliability sampling method or report a reliability coefficient for all key study variables, and few utilized a census or probability sampling frame. Implications are discussed and recommendations made for reporting of reliability in content analysis

String windings in the early universe

We study string dynamics in the early universe. Our motivation is the proposal of Brandenberger and Vafa, that string winding modes may play a key role in decompactifying three spatial dimensions. We model the universe as a homogeneous but anisotropic 9-torus filled with a gas of excited strings. We adopt initial conditions which fix the dilaton and the volume of the torus, but otherwise assume all states are equally likely. We study the evolution of the system both analytically and numerically to determine the late-time behavior. We find that, although dynamical evolution can indeed lead to three large spatial dimensions, such an outcome is not statistically favored.Comment: 26 pages, LaTeX, 4 eps figure

Hall and photoresponse measurements associated with ultraviolet and near ultraviolet degradation of thin zinc oxide films

Optical and electrical parameters of zinc oxide degradation during exposure to spectral radiatio

Investigation of the TOCA1-Cdc42 interaction

Transducer of Cdc42-dependent actin assembly protein 1 (TOCA1) is an effector of the Rho family small G protein Cdc42. It contains a membrane-deforming F-BAR domain as well as a Src homology 3 (SH3) domain and a G protein-binding homology region 1 (HR1) domain. TOCA1 binding to Cdc42 leads to actin rearrangements, which are thought to be involved in processes such as endocytosis, filopodia formation, and cell migration. We have solved the structure of the HR1 domain of TOCA1, providing the first structural data for this protein. We have found that the TOCA1 HR1, like the closely related CIP4 HR1, has interesting structural features that are not observed in other HR1 domains. We have also investigated the binding of the TOCA HR1 domain to Cdc42 and the potential ternary complex between Cdc42 and the G protein-binding regions of TOCA1 and a member of the Wiskott-Aldrich syndrome protein family, N-WASP. TOCA1 binds Cdc42 with micromolar affinity, in contrast to the nanomolar affinity of the N-WASP G protein-binding region for Cdc42. NMR experiments show that the Cdc42-binding domain from N-WASP is able to displace TOCA1 HR1 from Cdc42, whereas the N-WASP domain but not the TOCA1 HR1 domain inhibits actin polymerization. This suggests that TOCA1 binding to Cdc42 is an early step in the Cdc42-dependent pathways that govern actin dynamics, and the differential binding affinities of the effectors facilitate a handover from TOCA1 to N-WASP, which can then drive recruitment of the actin-modifying machinery.JRW is supported by a Herchel Smith studentship. JLG is supported by a Wellcome Trust Research Career Development Fellowship (WT095829AIA), European Research Council Starting Grant (281971) and Gurdon Institute funding provided by the Wellcome Trust (092096) and CRUK (C6946/A14492). HMF is supported by a Wellcome Trust PhD Studentship (WT099740Z12Z). We would like to thank Dr A Walrant for help with the pyrene actin assays and liposome preparation. We are also grateful to Dr J.R. Peterson (Fox Chase Cancer Center) for human TOCA1 clones.This is the final version of the article. It first appeared from the American Society for Biochemistry and Molecular Biology via http://dx.doi.org/10.1074/jbc.M116.72429

Truncating first-order Dyson-Schwinger equations in Coulomb-Gauge Yang-Mills theory

The non-perturbative domain of QCD contains confinement, chiral symmetry breaking, and the bound state spectrum. For the calculation of the latter, the Coulomb gauge is particularly well-suited. Access to these non-perturbative properties should be possible by means of the Green's functions. However, Coulomb gauge is also very involved, and thus hard to tackle. We introduce a novel BRST-type operator r, and show that the left-hand side of Gauss' law is r-exact. We investigate a possible truncation scheme of the Dyson-Schwinger equations in first-order formalism for the propagators based on an instantaneous approximation. We demonstrate that this is insufficient to obtain solutions with the expected property of a linear-rising Coulomb potential. We also show systematically that a class of possible vertex dressings does not change this result.Comment: 22 pages, 4 figures, 1 tabl

Correlation between microstructure and magnetotransport in organic semiconductor spin valve structures

We have studied magnetotransport in organic-inorganic hybrid multilayer junctions. In these devices, the organic semiconductor (OSC) Alq$_3$ (tris(8-hydroxyquinoline) aluminum) formed a spacer layer between ferromagnetic (FM) Co and Fe layers. The thickness of the Alq$_3$ layer was in the range of 50-150 nm. Positive magnetoresistance (MR) was observed at 4.2 K in a current perpendicular to plane geometry, and these effects persisted up to room temperature. The devices' microstructure was studied by X-ray reflectometry, Auger electron spectroscopy and polarized neutron reflectometry (PNR). The films show well-defined layers with modest average chemical roughness (3-5 nm) at the interface between the Alq$_3$ and the surrounding FM layers. Reflectometry shows that larger MR effects are associated with smaller FM/Alq$_3$ interface width (both chemical and magnetic) and a magnetically dead layer at the Alq$_3$/Fe interface. The PNR data also show that the Co layer, which was deposited on top of the Alq$_3$, adopts a multi-domain magnetic structure at low field and a perfect anti-parallel state is not obtained. The origins of the observed MR are discussed and attributed to spin coherent transport. A lower bound for the spin diffusion length in Alq$_3$ was estimated as $43 \pm 5$ nm at 80 K. However, the subtle correlations between microstructure and magnetotransport indicate the importance of interfacial effects in these systems.Comment: 21 pages, 11 figures and 2 table