Magnetic domain observation of hydrogenation disproportionation desorption recombination processed Nd－Fe－B powder with a high-resolution Kerr microscope using ultraviolet light

A Kerr microscope that uses ultraviolet (UV) light for high-resolution domain observation was built, and the domain structure and magnetization process of hydrogenation disproportionation desorption recombination (HDDR) powder were examined. The UV Kerr microscope could observe nanometer-sized domain patterns. Applying a dc field of 1.0 kOe to HDDR powder at a desorption recombination (DR) time of 12 min produced abrupt wall motion. The pinning force exerted by the grain boundaries is inadequate for producing high coercivity because the Nd-rich phase layers along these boundaries are absent at a DR time of 12 min. For HDDR powder at a DR time greater than 14 min, changing the magnetic field by up to 1.0 kOe produced no observable wall motion. It follows that the high coercivity of HDDR powder is due to domain wall pinning at the grain boundaries

Dense, Fe-rich Ejecta in Supernova Remnants DEM L238 and DEM L249: A New Class of Type Ia Supernova?

We present observations of two LMC supernova remnants (SNRs), DEM L238 and DEM L249, with the Chandra and XMM-Newton X-ray satellites. Bright central emission, surrounded by a faint shell, is present in both remnants. The central emission has an entirely thermal spectrum dominated by strong Fe L-shell lines, with the deduced Fe abundance in excess of solar and not consistent with the LMC abundance. This Fe overabundance leads to the conclusion that DEM L238 and DEM L249 are remnants of thermonuclear (Type Ia) explosions. The shell emission originates in gas swept up and heated by the blast wave. A standard Sedov analysis implies about 50 solar masses in both swept-up shells, SNR ages between 10,000 and 15,000 yr, low (< 0.05 cm^-3) preshock densities, and subluminous explosions with energies of 3x10^50 ergs. The central Fe-rich supernova ejecta are close to collisional ionization equilibrium. Their presence is unexpected, because standard Type Ia SNR models predict faint ejecta emission with short ionization ages. Both SNRs belong to a previously unrecognized class of Type Ia SNRs characterized by bright interior emission. Denser than expected ejecta and/or a dense circumstellar medium around the progenitors are required to explain the presence of Fe-rich ejecta in these SNRs. Substantial amounts of circumstellar gas are more likely to be present in explosions of more massive Type Ia progenitors. DEM L238, DEM L249, and similar SNRs could be remnants of ``prompt'' Type Ia explosions with young (~100 Myr old) progenitors.Comment: 24 pages, 8 figures, ApJ, in pres

A Study of the Populations of X-ray Sources in the Small Magellanic Cloud with ASCA

The Advanced Satellite for Cosmology and Astrophysics (ASCA) has made multiple observations of the Small Magellanic Cloud (SMC). X-ray mosaic images in the soft (0.7--2.0 keV) and hard (2.0--7.0 keV) bands are separately constructed, and the latter provides the first hard X-ray view of the SMC. We extract 39 sources from the two-band images with a criterion of S/N>5, and conduct timing and spectral analyses for all of these sources. Coherent pulsations are detected from 12 X-ray sources; five of which are new discoveries. Most of the 12 X-ray pulsars are found to exhibit long-term flux variabilities, hence they are likely to be X-ray binary pulsars (XBPs). On the other hand, we classify four supernova remnants (SNRs) as thermal SNRs, because their spectra exhibit emission lines from highly ionized atoms. We find that XBPs and thermal SNRs in the SMC can be clearly separated by their hardness ratio (the ratio of the count rate between the hard and soft bands). Using this empirical grouping, we find many XBP candidates in the SMC, although no pulsations have yet been detected from these sources. Possible implications on the star-formation history and evolution of the SMC are presented by a comparison of the source populations in the SMC and our Galaxy.Comment: 11 pages, 39 Figures, to be published in ApJ Supplement. Tables (body and figures also) are available at http://www-cr.scphys.kyoto-u.ac.jp/member/jun/job

The intriguing nature of the high energy gamma ray source XSSJ12270-4859

The nature of the hard X-ray source XSSJ12270-4859 is still unclear though it was claimed to be a magnetic Cataclysmic Variable. We here present a broad-band X-ray and gamma ray study based on a recent XMM-Newton observation and archival INTEGRAL and RXTE data. From the Fermi/LAT 1-year point source catalogue, we tentatively associate XSSJ12270-4859 with 1FGLJ1227.9-4852, a source of high energy gamma rays with emission up to 10GeV. We complement the study with UV photometry from XMM-Newton and ground-based optical and near-IR photometry. The X-ray emission is highly variable showing flares and intensity dips. The X-ray flares consist of flare-dip pairs. Flares are also detected in the UV range but not the dips. Aperiodic dipping behaviour is also observed during X-ray quiescence but not in the UV. The 0.2-100keV spectrum is featureless and described by a power law model with Gamma=1.7. The 100MeV-10GeV spectrum is instead represented by a power law index of 2.45. The luminosity ratio between 0.1-100GeV and 0.2--100keV is ~0.8, hence the GeV emission is a significant component of the total energy output. Furthermore, the X-ray spectrum does not greatly change during flares, quiescence and the dips seen in quiescence but it hardens during the post-flare dips. Optical photometry reveals a period of 4.32hr likely related to the binary orbit. Near-IR, possibly ellipsoidal, variations are detected. Large amplitude variability on shorter (tens mins) timescales are found to be non-periodic. The observed variability at all wavelengths and the spectral characteristics strongly favour a low-mass atypical low-luminosity X-ray binary and are against a Cataclysmic Variable nature. The association with a Fermi/LAT high energy gamma ray source further strengths this interpretation.Comment: 12 pages, 11 figures, 3 tables; Accepted for publication in Astronomy & Astrophysics Main Journ

cDNA display: a novel screening method for functional disulfide-rich peptides by solid-phase synthesis and stabilization of mRNA–protein fusions

We report a robust display technology for the screening of disulfide-rich peptides, based on cDNA–protein fusions, by developing a novel and versatile puromycin-linker DNA. This linker comprises four major portions: a ‘ligation site’ for T4 RNA ligase, a ‘biotin site’ for solid-phase handling, a ‘reverse transcription primer site’ for the efficient and rapid conversion from an unstable mRNA–protein fusion (mRNA display) to a stable mRNA/cDNA–protein fusion (cDNA display) whose cDNA is covalently linked to its encoded protein and a ‘restriction enzyme site’ for the release of a complex from the solid support. This enables not only stabilizing mRNA–protein fusions but also promoting both protein folding and disulfide shuffling reactions. We evaluated the performance of cDNA display in different model systems and demonstrated an enrichment efficiency of 20-fold per selection round. Selection of a 32-residue random library against interleukin-6 receptor generated novel peptides containing multiple disulfide bonds with a unique linkage for its function. The peptides were found to bind with the target in the low nanomolar range. These results show the suitability of our method for in vitro selections of disulfide-rich proteins and other potential applications

Xanthogranuloma of the intrasellar region presenting in pituitary dysfunction: a case report

<p>Abstract</p> <p>Introduction</p> <p>Differentiation of cystic mass lesions of the sellar and parasellar regions may pose a diagnostic dilemma for physicians, neurosurgeons, radiologists and pathologists involved in treating patients with these entities. A considerable number of tumors previously identified as craniopharyngiomas may, in fact, have been xanthogranulomas. We report a case of pituitary dysfunction caused by xanthogranuloma of the intrasellar region.</p> <p>Case presentation</p> <p>A 47-year-old man of Japanese descent presented to our institution with a tumor located exclusively in the intrasellar region which manifested as severe hypopituitarism. MRI revealed a clearly defined intrasellar mass that was heterogeneously hyperintense on T1-weighted images and markedly hypointense on T2-weighted images. We preoperatively diagnosed the patient with Rathke's cleft cyst or non-functioning pituitary adenoma. Although the tumor was completely removed using a transsphenoidal approach, the improvement of the patient's endocrine function was marginal, and continued endocrine replacement therapy was needed. Postoperatively, a histological examination revealed the tumor to be a xanthogranuloma of the intrasellar region. His visual field defects and headache improved.</p> <p>Conclusion</p> <p>Because diagnosis depends on surgical intervention and xanthogranulomas of the intrasellar region are very rare, the natural history of xanthogranuloma is still unknown. Therefore, this entity is difficult to diagnose preoperatively. We suggest that xanthogranuloma should be included in the differential diagnosis, even in the case of sellar lesions, to formulate appropriate postoperative management and improve endocrine outcomes.</p

X-ray emission from stainless steel foils irradiated by femtosecond petawatt laser pulses

We report about nonlinear growth of x-ray emission intensity emitted from plasma generated by femtosecond petawatt laser pulses irradiating stainless steel foils. X-ray emission intensity increases as ∼ I 4.5 with laser intensity I on a target. High spectrally resolved x-ray emission from front and rear surfaces of 5 μm thickness stainless steel targets were obtained at the wavelength range 1.7-2.1 Å, for the first time in experiments at femtosecond petawatt laser facility J-KAREN-P. Total intensity of front x-ray spectra three times dominates to rear side spectra for maximum laser intensity I ≈ 3.21021 W/cm2. Growth of x-ray emission is mostly determined by contribution of bremsstrahlung radiation that allowed estimating bulk electron plasma temperature for various magnitude of laser intensity on target