2,620 research outputs found
Analysis of Laser ARPES from BiSrCaCuO in superconductive state: angle resolved self-energy and fluctuation spectrum
We analyze the ultra high resolution laser angle resolved photo-emission
spectroscopy (ARPES) intensity from the slightly underdoped
BiSrCaCuO in the superconductive (SC) state. The
momentum distribution curves (MDC) were fitted at each energy \w employing
the SC Green's function along several cuts perpendicular to the Fermi surface
with the tilt angle with respect to the nodal cut. The clear
observation of particle-hole mixing was utilized such that the complex
self-energy as a function of is directly obtained from the fitting.
The obtained angle resolved self-energy is then used to deduce the Eliashberg
function \alpha^2 F^{(+)}(\th,\w) in the diagonal channel by inverting the
d-wave Eliashberg equation using the maximum entropy method. Besides a broad
featureless spectrum up to the cutoff energy , the deduced exhibits two peaks around 0.05 eV and 0.015 eV. The former and the broad
feature are already present in the normal state, while the latter emerges only
below . Both peaks become enhanced as is lowered or the angle
moves away from the nodal direction. The implication of these findings are
discussed.Comment: 7 pages, 5 figures, summited to PR
Quantum Separability of the vacuum for Scalar Fields with a Boundary
Using the Green's function approach we investigate separability of the vacuum
state of a massless scalar field with a single Dirichlet boundary. Separability
is demonstrated using the positive partial transpose criterion for effective
two-mode Gaussian states of collective operators. In contrast to the vacuum
energy, entanglement of the vacuum is not modified by the presence of the
boundary.Comment: 4 pages, 1 figure, Revtex, minor corrections. submitted to Phy. Rev.
The Actinobacillus pleuropneumoniae HMW1C-Like Glycosyltransferase Mediates N-Linked Glycosylation of the Haemophilus influenzae HMW1 Adhesin
The Haemophilus influenzae HMW1 adhesin is an important virulence exoprotein that is secreted via the two-partner secretion pathway and is glycosylated at multiple asparagine residues in consensus N-linked sequons. Unlike the heavily branched glycans found in eukaryotic N-linked glycoproteins, the modifying glycan structures in HMW1 are mono-hexoses or di-hexoses. Recent work demonstrated that the H. influenzae HMW1C protein is the glycosyltransferase responsible for transferring glucose and galactose to the acceptor sites of HMW1. An Actinobacillus pleuropneumoniae protein designated ApHMW1C shares high-level homology with HMW1C and has been assigned to the GT41 family, which otherwise contains only O-glycosyltransferases. In this study, we demonstrated that ApHMW1C has N-glycosyltransferase activity and is able to transfer glucose and galactose to known asparagine sites in HMW1. In addition, we found that ApHMW1C is able to complement a deficiency of HMW1C and mediate HMW1 glycosylation and adhesive activity in whole bacteria. Initial structure-function studies suggested that ApHMW1C consists of two domains, including a 15-kDa N-terminal domain and a 55-kDa C-terminal domain harboring glycosyltransferase activity. These findings suggest a new subfamily of HMW1C-like glycosyltransferases distinct from other GT41 family O-glycosyltransferases
Evaluation of combinatorial cis-regulatory elements for stable gene expression in chicken cells
This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Recent successes in biotechnological application of birds are based on their unique physiological traits such as unlimited manipulability onto developing embryos and simple protein constituents of the eggs. However it is not likely that target protein is produced as kinetically expected because various factors affect target gene expression. Although there have been various attempts to minimize the silencing of transgenes, a generalized study that uses multiple cis-acting elements in chicken has not been made. The aim of the present study was to analyze whether various cis-acting elements can help to sustain transgene expression in chicken fibroblasts.
Results: We investigated the optimal transcriptional regulatory elements for enhancing stable transgene expression in chicken cells. We generated eight constructs that encode enhanced green fluorescent protein (eGFP) driven by either CMV or CAG promoters (including the control), containing three types of key regulatory elements: a chicken lysozyme matrix attachment region (cMAR), 5′-DNase I-hypersensitive sites 4 (cHS4), and the woodchuck hepatitis virus posttranscriptional regulatory element (WPRE). Then we transformed immortalized chicken embryonic fibroblasts with these constructs by electroporation, and after cells were expanded under G418 selection, analyzed mRNA levels and mean fluorescence intensity (MFI) by quantitative real-time PCR and flow cytometry, respectively. We found that the copy number of each construct significantly decreased as the size of the construct increased (R2 = 0.701). A significant model effect was found in the expression level among various constructs in both mRNA and protein (P < 0.0001). Transcription with the CAG promoter was 1.6-fold higher than the CMV promoter (P = 0.027) and the level of eGFP expression activity in cMAR- or cHS4-flanked constructs increased by two- to three-fold compared to the control CMV or CAG promoter constructs. In addition, flow cytometry analysis showed that constructs having cis-acting elements decreased the level of gene silencing as well as the coefficient of variance of eGFP-expressing cells (P < 0.0001).
Conclusions: Our current data show that an optimal combination of cis-acting elements and promoters/enhancers for sustaining gene expression in chicken cells is suggested. These results provide important information for avian transgenesis and gene function studies in poultry
Recovery of Heavy Minerals from Korean Beach Sand
In order to establish the optimized recovery process for heavy minerals from beach sand, we investigated the physical separation methods such as gravity and magnetic separation followed by mineralogical characterization. There was clear relationship between the particle size
and the heavy mineral content that the heavy minerals were mostly concentrated in the particles below 100mesh. Grav-ity separation using the spiral and shaking table sepa-rators made it possible to concentrate heavy minerals by rejecting the light and coarse particles consist mainly
of quartz. The high-intensity magnetic separator and subsequent induced magnetic separator were applied to fractionate magnetic particles into three fractions accor-ding to their magnetic susceptibility. The content of TiO, of high magnetic susceptible ilmenite-rich fraction was 43.98wt.% while those of ZrO2 of non-magnetic and magnetic residue were 6.78wt.% and 3.11 wt. %. respectively
Robust Co-catalytic Performance of Nanodiamonds Loaded on WO3 for the Decomposition of Volatile Organic Compounds under Visible Light
Proper co-catalysts (usually noble metals), combined with semiconductor materials, are commonly needed to maximize the efficiency of photocatalysis. Search for cost-effective and practical alternatives for noble-metal co-catalysts is under intense investigation. In this work, nanodiamond (ND), which is a carbon nanomaterial with a unique sp(3)(core)/sp(2)(shell) structure, was combined with WO3 (as an alternative co-catalyst for Pt) and applied for the degradation of volatile organic compounds under visible light. NDs-loaded WO3 showed a highly enhanced photocatalytic activity for the degradation of acetaldehyde (similar to 17 times higher than bare WO3), which is more efficient than other well-known co-catalysts (Ag, Pd, Au, and CuO) loaded onto WO3 and comparable to Pt-loaded WO3. Various surface modifications of ND and photoelectochemical measurements revealed that the graphitic carbon shell (sp(2)) on the diamond core (spa) plays a crucial role in charge separation and the subsequent interfacial charge transfer. As a result, ND/WO3 showed much higher production of OH radicals than bare WO3 under visible light. Since ND has a highly transparent characteristic, the light shielding that is often problematic with other carbon-based co-catalysts was considerably lower with NDs-loaded WO3. As a result, the photocatalytic activity of NDs/WO3 was higher than that of WO3 loaded with other carbon-based co-catalysts (graphene oxide or reduced graphene oxide). A range of spectroscopic and photo(electro)chemical techniques were systematically employed to investigate the properties of NDs-loaded WO3. ND is proposed as a cost-effective and practical nanomaterial to replace expensive noble-metal co-catalysts.1124Ysciescopu
Obstructed D-Branes in Landau-Ginzburg Orbifolds
We study deformations of Landau-Ginzburg D-branes corresponding to obstructed
rational curves on Calabi-Yau threefolds. We determine D-brane moduli spaces
and D-brane superpotentials by evaluating higher products up to homotopy in the
Landau-Ginzburg orbifold category. For concreteness we work out the details for
lines on a perturbed Fermat quintic. In this case we show that our results
reproduce the local analytic structure of the Hilbert scheme of curves on the
threefold.Comment: 44 pages; v3: typos correcte
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