Central Spiral Structure of Molecular Gas in Maffei 2

Distribution and kinematics of molecular gas in the central region of the barred spiral galaxy Maffei 2 were investigated using a data set of 12CO(1-0), 12CO(2-1), CS(2-1) lines and 103 GHz continuum. We found that the offset ridges along the kpc-scale bar continue to the central spiral structure embedded in the weak oval structure which is regarded as x2 orbit in the bar potential. The spiral structure continues toward the center diverging from the oval structure. The size of these structures is less than R ~ 100 pc. The mass concentration within R = 35 pc is estimated to be 2 X 10^8 Mo. The high mass concentration is consistent with theoretical predictions concerning the creation of such a nuclear spiral structure. A comparison with the tracers of dense gas and star-forming region suggests that the dense molecular gas traced by CS(2-1) line is formed at the crossing points of x1 and x2 orbits and the star-forming region appears after 2 X 10^5 yr which is comparable with the free-fall time of the dense gas traced by the CS line (~ 10^5 cm^-3).Comment: 7 pages, 10 figures, Publication of Astronomical Society of Japan, in pres

Posterior cervical spine arthrodesis with laminar screws: a report of two cases

We performed fixation using laminar screws in 2 patients in whom lateral mass screws, pedicle screws or transarticular screws could not be inserted. One was a 56-year-old woman who had anterior atlantoaxial subluxation (AAS). When a guide wire was inserted using an imaging guide, the hole bled massively. We thought the re-insertion of a guide wire or screw would thus increase the risk of vascular injury, so we used laminar screws. The other case was an 18-year-old man who had a hangman fracture. Preoperative magnetic resonance angiography showed occlusion of the left vertebral artery. A laminar screw was inserted into the patent side (i.e., the right side of C2). Cervical pedicle screws are the most biomechanically stable screws. However, their use carries a high risk of neurovascular complications during screw insertion, because the cervical pedicle is small and is adjacent laterally to the vertebral artery, medially to the spinal cord, and vertically to the nerve roots. Lateral mass screws are also reported to involve a risk of neurovascular injuries. The laminar screw method was thus thought to be useful, since arterial injuries could thus be avoided and it could also be used as a salvage modality for the previous misinsertion.</p

Effect of Grain Boundary on Pseudo-elastic Deformation of Cu-Zn-Si Bicrystal of Shape Memory Alloy

Two sorts of Cu-Zn-Si pseudo-elastic bicrystals of shape memory alloy were tested in tension to know the effects of the grain boundary. The remaining martensites were observed in the vicinity of the grain boundary, and the propriety of analyses through use of m/m。 and Nᵢj values and of the compatibility of the plastic strain were studied. The variant of martensite occurring primarily in each grain during deformation, can be predicted with use of them value (shear factor of the variant) in general. The analyses through use of m/mᵢ and Nᵢj values and the equations of the plastic strain compatibility are sufficiently useful to know the variant of martensite nucleated additionally in the vicinity of the grain boundary. However, the possibility of activation of slip must be considered in this case. The reversible strain of the isoaxial bicrystal is larger than that of the non-isoaxial bicrystal. However, the relation between the reversible strain and the misorientation of bicrystal is not yet sufficiently known

Two-photon interference of photon pairs created in photonic crystal fibers

We investigate a method to produce photon pairs by four-wave mixing in photonic crystal fibers (PCFs). By controlling the wavelength of the pump light, which determines the phase matching condition for four-wave mixing, we can obtain a broader spectrum of photon pairs than undesired Raman-scattered photons. We observe two-photon interference of photon pairs from a PCF with the help of an unbalanced Mach-Zehnder interferometer. Two-photon interference fringes with 83% visibility, which exceeds the classical limit of 50%, are obtained.Comment: 5 pages, 6 figures, to be published in JPS

A Case of Surgery for Kyphosis of the Thoracolumbar Spine in an Elderly Patient with Dysphagia

Here we report a case of surgery for kyphosis of the thoracolumbar spine in an elderly patient, in whom surgery was performed because the patient had developed intractable digestive symptoms. The case was that of a 76-year-old female with complaints of back pain and dysphagia. When videofluoroscopic examination (VF) of swallowing was performed in the cardia of the stomach, images that indicated stagnation and the reflux of food were observed. It was easier for the patient to swallow food in the extension position. We performed corrective fusion of the posterior spine. After the surgery, the kyphosis angle was improved to 27°, the patient's back pain was alleviated, and it became easier for the patient to swallow food. VF also showed that the patient's difficulties with the passage of food had improved. We believe that surgery is a good treatment option for cases of kyphosis with digestive symptoms and deteriorating activities of daily living (ADL), even in the absence of pain and paralysis. VF is also useful for performing evaluations before and after surgery