1,458 research outputs found
Breakdown of Conventional Factorization for Isolated Photon Cross Sections
Using as an example, we show that the
conventional factorization theorem in perturbative quantum chromodynamics
breaks down for isolated photon cross sections in a well defined part of phase
space. Implications and physical consequences are discussed.Comment: 11 pages, RevTex, 1 figure in postscrip
Proper Scaling of the Anomalous Hall Effect
Working with epitaxial films of Fe, we succeeded in independent control of
different scattering processes in the anomalous Hall effect. The result
appropriately accounted for the role of phonons, thereby clearly exposing the
fundamental flaws of the standard plot of the anomalous Hall resistivity versus
longitudinal resistivity. A new scaling has been thus established that allows
an unambiguous identification of the intrinsic Berry curvature mechanism as
well as the extrinsic skew scattering and side-jump mechanisms of the anomalous
Hall effect.Comment: 5 pages, 4 figure
Exploration of chlamydial type III secretion system reconstitution in Escherichia coli
BACKGROUND: Type III secretion system is a virulent factor for many pathogens, and is thought to play multiple roles in the development cycle and pathogenesis of chlamydia, an important human pathogen. However, due to the obligate intracellular parasitical nature of chlamydiae and a lack of convenient genetic methodology for the organisms, very limited approaches are available to study the chlamydial type III secretion system. In this study, we explored the reconstitution of a chlamydial type III secretion in Escherichia coli. RESULTS: We successfully cloned all 6 genomic DNA clusters of the chlamydial type III secretion system into three bacterial plasmids. 5 of the 6 clusters were found to direct mRNA synthesis from their own promoters in Escherichia coli transformed with the three plasmids. Cluster 5 failed to express mRNA using its own promoters. However, fusion of cluster 5 to cluster 6 resulted in the expression of cluster 5 mRNA. Although only two of the type III secretion system proteins were detected transformed E. coli due to limited antibody availability, type III secretion system-like structures were detected in ultrathin sections in a small proportion of transformed E. coli. CONCLUSIONS: We have successfully generated E. coli expressing all genes of the chlamydial type III secretion system. This serves as a foundation for optimal expression and assembly of the recombinant chlamydial type III secretion system, which may be extremely useful for the characterization of the chlamydial type III secretion system and for studying its role in chlamydial pathogenicity
Isolated Prompt Photon Production
We show that the conventionally defined partonic cross section for the
production of isolated prompt photons is not an infrared safe quantity. We work
out the case of in detail, and we discuss implications
for hadron reactions such as .Comment: 8 pages, latex2e, 2 figures, uses Moriond.sty; Invited paper
presented by E. L. Berger at the XXXIInd Rencontres de Moriond, QCD and High
Energy Hadronic Interactions, Les Arcs, Savoie, France, March 22 - 29, 199
Significant Improvement in TiOâ‚‚ Photocatalytic Activity through Controllable ZrOâ‚‚ Deposition
ZrO2 was deposited on anatase TiO2 nanoparticles using 5-80 cycles of atomic layer deposition (ALD). The photocatalytic activity of all samples was evaluated based on the degradation of methylene blue (MB) solution under UV light. The TiO2 sample with 45 cycles of ZrO2 deposition (45c-Zr/TiO2, 1.1 wt% ZrO2) was proved to be the most efficient catalyst with a degradation kinetic constant 10 times larger than that of the pure TiO2 sample. All samples were characterized using inductively coupled plasma atomic emission spectroscopy (ICP-AES), nitrogen adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra analysis (UV-DRS), Raman and photoluminescence (PL) techniques. The high photocatalytic activity of 45c-Zr/TiO2 can be attributed to stronger adsorption in the ultraviolet region and a reduction in the recombination rate of electron/hole pairs
Isolated Prompt Photon Cross Sections
We show that the conventionally defined partonic cross section for the
production of isolated prompt photons is not an infrared safe quantity. We work
out the case of , and discuss implications for hadron
reactions.Comment: 4 pages, LaTeX, 2 postscript figures, uses sprocl.sty. Invited paper
presented by E. L. Berger at DPF'96, 1996 Meeting of the Division of
Particles and Fields of the American Physical Society, Minneapolis, MN,
August 10-15, 1996. Report-no: ANL-HEP-CP-96-7
Photoelectron properties of DNA and RNA bases from many-body perturbation theory
The photoelectron properties of DNA and RNA bases are studied using many-body
perturbation theory within the GW approximation, together with a recently
developed Lanczos-chain approach. Calculated vertical ionization potentials,
electron affinities, and total density of states are in good agreement with
experimental values and photoemission spectra. The convergence benchmark
demonstrates the importance of using an optimal polarizability basis in the GW
calculations. A detailed analysis of the role of exchange and correlation in
both many-body and density-functional theory calculations shows that while
self-energy corrections are strongly orbital-dependent, they nevertheless
remain almost constant for states that share the same bonding character.
Finally, we report on the inverse lifetimes of DNA and RNA bases, that are
found to depend linearly on quasi-particle energies for all deep valence
states. In general, our G0W0-Lanczos approach provides an efficient yet
accurate and fully converged description of quasiparticle properties of five
DNA and RNA bases
Na+-leak channel, non-selective (NALCN) regulates myometrial excitability and facilitates successful parturition
Background/Aims: Uterine contractility is controlled by electrical signals generated by myometrial smooth muscle cells. Because aberrant electrical signaling may cause inefficient uterine contractions and poor reproductive outcomes, there is great interest in defining the ion channels that regulate uterine excitability. In human myometrium, the Na+ leak channel, non-selective (NALCN) contributes to a gadolinium-sensitive, Na+-dependent leak current. The aim of this study was to determine the role of NALCN in regulating uterine excitability and examine its involvement in parturition. Methods: Wildtype C57BL/6J mice underwent timed-mating and NALCN uterine expression was measured at several time points across pregnancy including pregnancy days 7, 10, 14, 18 and 19. Sharp electrode current clamp was used to measure uterine excitability at these same time points. To determine NALCN’s contribution to myometrial excitability and pregnancy outcomes, we created smooth-muscle-specific NALCN knockout mice by crossing NALCNfx/fx mice with myosin heavy chain Cre (MHCCreeGFP) mice. Parturition outcomes were assessed by observation via surveillance video recording cre control, flox control, smNALCN+/-, and smNALCN-/- mice. Myometrial excitability was compared between pregnancy day 19 flox controls and smNALCN-/- mice. Results: We found that in the mouse uterus, NALCN protein levels were high early in pregnancy, decreased in mid and late pregnancy, and then increased in labor and postpartum. Sharp electrode current clamp recordings of mouse longitudinal myometrial samples from pregnancy days 7, 10, 14, 18, and 19 revealed day-dependent increases in burst duration and interval and decreases in spike density. NALCN smooth muscle knockout mice had reduced myometrial excitability exemplified by shortened action potential bursts, and an increased rate of abnormal labor, including prolonged and dysfunctional labor. Conclusions: Together, our findings demonstrate that the Na+ conducting channel NALCN contributes to the myometrial action potential waveform and is important for successful labor outcomes
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