Ferromagnetic redshift of the optical gap in GdN

We report measurements of the optical gap in a GdN film at temperatures from 300 to 6K, covering both the paramagnetic and ferromagnetic phases. The gap is 1.31eV in the paramagnetic phase and red-shifts to 0.9eV in the spin-split bands below the Curie temperature. The paramagnetic gap is larger than was suggested by very early experiments, and has permitted us to refine a (LSDA+U)-computed band structure. The band structure was computed in the full translation symmetry of the ferromagnetic ground state, assigning the paramagnetic-state gap as the average of the majority- and minority-spin gaps in the ferromagnetic state. That procedure has been further tested by a band structure in a 32-atom supercell with randomly-oriented spins. After fitting only the paramagnetic gap the refined band structure then reproduces our measured gaps in both phases by direct transitions at the X point.Comment: 5 pages, 4 figure

Tiling the plane without supersymmetry

We present a way of tiling the plane with a regular hexagonal network of defects. The network is stable and follows in consequence of the three-junctions that appear in a model of two real scalar fields that presents $Z_3$ symmetry. The $Z_3$ symmetry is effective in both the vacuum and defect sectors, and no supersymmetry is required to build the network.Comment: Revtex, 4 pages, 1 ps figure; version to appear in Phys. Rev. Let

Vortex dynamics in layered superconductors with correlated defects: influence of interlayer coupling

We report a detailed study of the vortex dynamics and vortex phase diagrams of two amorphous Ta_0.3Ge_0.7/Ge multilayered films with intrinsic coplanar defects, but different interlayer coupling. A pinned Bose-glass phase in the more weakly coupled sample exists only below a cross-over field H* in striking contrast to the strongly coupled film. Above H* the flux lines are thought to break up into pancake vortices and the cross-over field is significantly increased when the field is aligned along the extended defects. The two films show different vortex creep excitations in the Bose-glass phase.Comment: zip file: 1 RevTex, 5 figures (png

An examination of the effects of self-regulatory focus on the perception of the media richness: the case of email

Communication is a key element in organizations’ business success. The media richness theory and the channel expansion theory are two of the most influential theories regarding the selection and use of communication media in organizations; however, literature has focused little on the effects of self-regulation by managers and employees in these theories. To analyze these topics, this study develops an empirical investigation by gathering data from 600 managers and employees using a questionnaire. The results suggest that the perception of media richness is positively affected when the individual shows a promotion focus or strategy.Peer ReviewedPostprint (author’s final draft

Bags, junctions, and networks of BPS and non-BPS defects

We investigate several models of coupled scalar fields that present discrete Z_2, Z_2 x Z_2, Z_3 and other symmetries. These models support topological domain wall solutions of the BPS and non-BPS type. The BPS solutions are stable, but the stability of the non-BPS solutions may depend on the parameters that specify the models. The BPS and non-BPS states give rise to bags, and also to three-junctions that may allow the presence of networks of topological defects. In particular, we show that the non-BPS defects of a specific model that engenders the Z_3 symmetry give rise to a stable regular hexagonal network of domain walls.Comment: Revtex, 16 pages, 6 ps figures; Shorter version to be published in Phys. Rev.

Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation

We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis

Direct Measurement of the Top Quark Mass at D0

We determine the top quark mass m_t using t-tbar pairs produced in the D0 detector by \sqrt{s} = 1.8 TeV p-pbar collisions in a 125 pb^-1 exposure at the Fermilab Tevatron. We make a two constraint fit to m_t in t-tbar -> b W^+bbar W^- final states with one W boson decaying to q-qbar and the other to e-nu or mu-nu. Likelihood fits to the data yield m_t(l+jets) = 173.3 +- 5.6 (stat) +- 5.5 (syst) GeV/c^2. When this result is combined with an analysis of events in which both W bosons decay into leptons, we obtain m_t = 172.1 +- 5.2 (stat) +- 4.9 (syst) GeV/c^2. An alternate analysis, using three constraint fits to fixed top quark masses, gives m_t(l+jets) = 176.0 +- 7.9 (stat) +- 4.8 (syst) GeV/C^2, consistent with the above result. Studies of kinematic distributions of the top quark candidates are also presented.Comment: 43 pages, 53 figures, 33 tables. RevTeX. Submitted to Phys. Rev.

Direct Measurement of the Top Quark Mass

We measure the top quark mass m_t using t tbar pairs produced in the D0 detector by root(s) = 1.8 TeV p pbar collisions in a 125 pb^-1 exposure at the Fermilab Tevatron. We make a two constraint fit to m_t in t tbar --> b W^+ bbar W^- final states with one W decaying to q qbar and the other to e nu or mu nu. Events are binned in fit mass versus a measure of probability for events to be signal rather than background. Likelihood fits to the data yield m_t = 173.3 +- 5.6 (stat) +- 6.2 (syst) GeV/c^2.Comment: 11 pages with 3 encapsulated PostScript figures and 1 encapsulated PostScript table included in the body of the articl

Optimization of facade design based on the impact of interior obstructions to daylighting

Overcrowding in the perimeter zone is an inevitable issue in residential rooms with limited space. Obstructions, such as furniture and household items, may block the existing windows, and therefore affect interior daylight conditions. A facade design approach is needed that simultaneously takes into account daylighting and the volume of usable space for obstructions in the perimeter zone of such rooms. This study simulates daylight distributions in a typical small residential room with obstructions in front of windows. The simulation consists of two parts. First, the effects on horizontal illuminances caused by different positions and shapes of obstructions are examined under an overcast sky. Second, the maximum usable space volumes for obstructions of 51 optimized facade configurations are calculated in terms of four window-to-wall ratios (WWRs). The results of this study show that optimizing the forms of facade design can increase the usable interior space volume and meet the daylighting requirements of Chinese standards for small residential rooms. Additionally, by using the optimized facade forms, a facade with a WWR value of 50% provides the maximum usable space for obstructions. Based on the above results, this paper presents two matrices that can help architects in selecting the appropriate fenestration methods and confirming the size of usable space and allocation for residents