1,147 research outputs found
Electronic Properties of Topological Materials: Optical Excitations in Moebius Conjugated Polymers
Electronic structures and optical excitations in Moebius conjugated polymers
are studied theoretically. Periodic and Moebius boundary conditions are applied
to the tight binding model of poly(para-phenylene), taking exciton effects into
account. We discuss that oligomers with a few structural units are more
effective than polymers for observations of effects of discrete wave numbers
that are shifted by the change in boundary condition. Next, calculations of
optical absorption spectra are reported. Certain components of optical
absorption for an electric field perpendicular to the polymer axis mix with
absorption spectra for an electric field parallel to the polymer axis.
Therefore, the polarization dependences of an electric field of light enable us
to detect whether conjugated polymers have the Moebius boundary.Comment: 10 pages, 6 figures, to be published in J. Phys. Soc. Jpn., Vol. 74
No. 2 (February, 2005), Letter sectio
Theory of Spin polarized Tunneling in Superconducting Sr2RuO4
A theory of tunneling conductance in ferromagnetic metal/insulator/triplet -
supercondcutor junctions is presented for unitary and non-unitary spin triplet
pairing states which are promising candidates for the superconducting paring
symmetry of Sr2RuO4. As the magnitude of the exchange interaction in the
ferromagnetic metal is increased, the conductance for the unitary pairing state
below the energy gap is reduced in contrast to the case for the non-unitary
pairing state
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Type I interferon-driven susceptibility to Mycobacterium tuberculosis is mediated by IL-1Ra.
The bacterium Mycobacterium tuberculosis (Mtb) causes tuberculosis and is responsible for more human mortality than any other single pathogen1. Progression to active disease occurs in only a fraction of infected individuals and is predicted by an elevated type I interferon (IFN) response2-7. Whether or how IFNs mediate susceptibility to Mtb has been difficult to study due to a lack of suitable mouse models6-11. Here, we examined B6.Sst1S congenic mice that carry the 'susceptible' allele of the Sst1 locus that results in exacerbated Mtb disease12-14. We found that enhanced production of type I IFNs was responsible for the susceptibility of B6.Sst1S mice to Mtb. Type I IFNs affect the expression of hundreds of genes, several of which have previously been implicated in susceptibility to bacterial infections6,7,15-18. Nevertheless, we found that heterozygous deficiency in just a single IFN target gene, Il1rn, which encodes interleukin-1 receptor antagonist (IL-1Ra), is sufficient to reverse IFN-driven susceptibility to Mtb in B6.Sst1S mice. In addition, antibody-mediated neutralization of IL-1Ra provided therapeutic benefit to Mtb-infected B6.Sst1S mice. Our results illustrate the value of the B6.Sst1S mouse to model IFN-driven susceptibility to Mtb, and demonstrate that IL-1Ra is an important mediator of type I IFN-driven susceptibility to Mtb infections in vivo
Temporomandibular Joint Relations of Bone and Lateral Pterygoid Muscle : A Computerized Tomography Study
This study utilized the imaging technique of computerized tomography (CT). Scans taken with a GE CT/N 8800 scanner of an adult cadaver and a 12-patient group were obtained through the Loma Linda University School of Dentistry, TMJ Department, and Loma Linda University Medical Center, Department of Neuroradiology.
The lateral scout image and a lateral cephalogram of the cadaver were compared using six angular measurements for facial type from Ricketts\u27 Cephalometric Analysis. The six measurements, Maxillary Depth, Facial Depth, Mandibular Arc, Mandibular Plane, Lower Face Height and Facial Axis, were found to be similar. This allowed the investigator to rely exclusively on CT scans to determine facial type and to image the hard and soft tissues of the TMJ.
Axial, coronal and sagittal images were used to measure axial condylar angle, transverse condylar head dimension, antero-posterior condylar head dimension, sagittal joint interval, central and medial coronal joint interval and the lateral pterygoid muscle angle and length. The mean values for these measurements were compared with respect to facial type. Although the small sample precluded statistical analysis, a trend toward a decreased lateral pterygoid muscle angle in an axial plane was noted in the dolichofacial group.
This application of CT was limited to studies of condylar position and lateral pterygoid muscle relations in different facial types. The relative non-invasiveness of the technique lends itself to other areas of concern to orthodontists. These include condylar and muscle responses to orthodontic treatment such as functional appliances and orthopedic mechanics. Longitudinal studies of growth and development of the lateral pterygoid muscle and other hard and soft tissues which are not imaged satisfactorily with conventional radiography are now possible
Tunneling current in triplet f-wave superconductors with horizontal lines of nodes
We calculate the tunneling conductance spectra of a
normal-metal/insulator/triplet superconductor using the
Blonder-Tinkham-Klapwijk (BTK) formulation. Possible states for the
superconductor are considered with horizontal lines of nodes, breaking the time
reversal symmetry. These results would be useful to discriminate between
pairing states in superonductor SrRuO and also in UPt.Comment: 12 pages, 7 figure
Edge states and determination of pairing symmetry in superconducting Sr2RuO4
We calculate the energy dispersion of the surface Andreev states and their
contribution to tunneling conductance for the order parameters with horizontal
and vertical lines of nodes proposed for superconducting Sr2RuO4. For vertical
lines, we find double peaks in tunneling spectra reflecting the van Hove
singularities in the density of surface states originating from the turning
points in their energy dispersion. For horizontal lines, we find a single
cusp-like peak at zero bias, which agrees very well with the experimental data
on tunneling in Sr2RuO4.Comment: 6 pages, 6 figures. V.2: comparison with experiment added and
discussion of horizontal nodes expanded. v.3: significant expansion: 1 figure
and 2 pages added. v.4: acknowledgements added. Additional viewgraphs with
experimental and theoretical curves superimposed are available at
http://www2.physics.umd.edu/~yakovenk/talks/Sr2RuO4
Theory of tunneling spectroscopy in superconducting Sr2RuO4
A theory for tunneling spectroscopy in normal metal /insulator/triplet
superconductor junction is presented. We assume two kinds of non-unitary
triplet superconducting states which are the most promising states for
SrRuO. The calculated conductance spectra showzero-bias peaks as
well as gap structures. The existences of residual components in the spectra
reflect the non-unitary properties of superconducting states.Comment: 5pages, 4figures(included), to be published in Phys.Rev.B 56, (1997
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