The X-ray afterglow flat segment in short GRB 051221A: Energy injection from a millisecond magnetar?

The flat segment lasting $\sim 10^4$ seconds in the X-ray afterglow of GRB051221A represents the first clear case of strong energy injection in the external shock of a short GRB afterglow. In this work, we show that a millisecond pulsar with dipole magnetic field $\sim 10^{14}$ Gauss could well account for that energy injection. The good quality X-ray flat segment thus suggests that the central engine of this short burst may be a millisecond magnetar.Comment: 4 pages including 1 figure, accepted for publication in MNRAS Letters, minor revisio

Comparison of AGASA data with CORSIKA simulation

An interpretation of AGASA (Akeno Giant Air Shower Array) data by comparing the experimental results with the simulated ones by CORSIKA (COsmic Ray SImulation for KASCADE) has been made. General features of the electromagnetic component and low energy muons observed by AGASA can be well reproduced by CORSIKA. The form of the lateral distribution of charged particles agrees well with the experimental one between a few hundred metres and 2000 m from the core, irrespective of the hadronic interaction model studied and the primary composition (proton or iron). It does not depend on the primary energy between 10^17.5 and 10^20 eV as the experiment shows. If we evaluate the particle density measured by scintillators of 5 cm thickness at 600 m from the core (S_0(600), suffix 0 denotes the vertically incident shower) by taking into account the similar conditions as in the experiment, the conversion relation from S_0(600) to the primary energy is expressed as E [eV] = 2.15 x 10^17 x S_0(600)^1.015, within 10% uncertainty among the models and composition used, which suggests the present AGASA conversion factor is the lower limit. Though the form of the muon lateral distribution fits well to the experiment within 1000 m from the core, the absolute values change with hadronic interaction model and primary composition. The slope of the rho_mu(600) (muon density above 1 GeV at 600 m from the core) vs. S_0(600) relation in experiment is flatter than that in simulation of any hadronic model and primary composition. Since the experimental slope is constant from 10^15 eV to 10^19 eV, we need to study this relation in a wide primary energy range to infer the rate of change of chemical composition with energy. keywords: cosmic ray, extensive air shower, simulation, primary energy estimation PACS number ; 96.40.De, 96.40.PqComment: 30 pages, 15 figures, accepted by Astroparticle Physics at 6. Dec 199

耳下腺気腫の2症例

耳下腺腫脹は臨床でしばしば遭遇する症状であり,原因となる病態は様々あるが,稀な疾患として耳下腺気腫がある.耳下腺気腫とは口腔内圧上昇によりステノン管から逆行性に空気が迷入し耳下腺腫大をきたす病態である.今回我々は耳下腺気腫の2症例を経験したので報告する.1症例目は6才男児で左耳下部の疼痛,腫脹を反復したため小児科から紹介.左耳下腺の圧迫でステノン管開口部から泡沫状唾液の流出があり,CT 検査でステノン管内に空気像を認め,左耳下腺気腫と診断された.経過中に頬を膨らませる習癖が確認され,習癖の禁止と抗菌薬処方で保存的に改善した.2症例目は43歳女性で左耳下部の腫脹と疼痛を主訴に当科を紹介受診.画像検査にて迷入した空気によるステノン管拡張と耳下腺内の空気像を認めたため,左耳下腺気腫と診断された.明らかな誘因は確認できず,抗菌薬処方で保存的に改善した.耳下腺腫脹には様々な原因が挙げられ,日常診療でも散見される症状である.急性発症で感染が疑われる場合には,抗菌薬投与で経過観察され軽快している症例も多数存在すると思われる.上述の経過観察とされる症例中にも耳下腺気腫である症例がいくつか含まれている可能性が示唆された.Parotid gland swelling is a familiar symptom in clinical practice and is caused by many conditions. However, swelling from pneumoparotitis is relatively rare. In pneumoparotitis, there is insufflation of air or gas in the retrograde direction up Stensen\u27s duct due to a rise in intraoral pressure. Here, we report two cases of pneumoparotitis. In Case 1, a 6-year-old boy was referred from the pediatrics department of our hospital because of recurrent swelling and pain in the left parotid region. Bubbles were seen in the saliva that discharged from Stensen\u27s duct by pressing the left parotid gland. In the bloodanalysis, serum amylase level was increased without an elevation of the white blood cell count and CRP. Computed tomography showed air in Stensen\u27s duct, and the diagnosis of pneumoparotitis of the left parotid gland was made. During follow-up, we found he had a habit of blowing his cheeks. The pneumoparotitis resolved after his habit was stopped and administration of antibiotics. In Case 2, a 43-year-old woman was referred to our hospital because of swelling and pain in the left parotid region. Blood analysis showed elevation of serum amylase without clear signs of infection. Radiologic evaluation demonstrated enlargement of Stensen\u27s duct due to retrograde passage of air and emphysema in the left parotid gland. The condition was diagnosed as pneumoparotitis of the left parotid gland. We were unable to identify a cause in this case. Symptoms were alleviated after the administration of antibiotics. Many diseases cause parotid gland swelling. We often encounter this symptom in clinical practice. In cases where infection of the parotid gland was suspected from the acute onset of symptoms, it seems that administration of antibiotics and follow-up were conducted without a thorough examination. Our findings suggest that pneumoparotitis may have occurred in some of these cases

Three-dimensional Structure of Nylon Hydrolase and Mechanism of Nylon-6 Hydrolysis

This research was originally published in the Journal of Biological Chemistry. Seiji Negoro, Naoki Shibata, Yusuke Tanaka, Kengo Yasuhira, Hiroshi Shibata, Haruka Hashimoto, Young-Ho Lee, Shohei Oshima, Ryuji Santa, Shohei Oshima, Kozo Mochiji, Yuji Goto, Takahisa Ikegami, Keisuke Nagai, Dai-ichiro Kato, Masahiro Takeo and Yoshiki Higuchi. Three-dimensional Structure of Nylon Hydrolase and Mechanism of Nylon-6 Hydrolysis. J. Biol. Chem. 2012; 287, 5079-5090. © the American Society for Biochemistry and Molecular Biolog

Black holes and the LHC: A review

In low-scale gravity models, a particle collider with trans-Planckian collision energies can be an ideal place for producing black holes because a large amount of energy can be concentrated at the collision point, which can ultimately lead to black hole formation. In this article, the theoretical foundation for microscopic higher dimensional black holes is reviewed and the possible production and detection at the LHC is described and critically examined.Comment: 65 pages, invited review article to be published in Progress of Particle and Nuclear Physic

Probing the Role of Magnetic-Field Variations in NOAA AR 8038 in Producing Solar Flare and CME on 12 May 1997

We carried out a multi-wavelength study of a CME and a medium-size 1B/C1.3 flare occurring on 12 May 1997. We present the investigation of magnetic-field variations in the NOAA Active Region 8038 which was observed on the Sun during 7--16 May 1997. Analyses of H{\alpha} filtergrams and MDI/SOHO magnetograms revealed continual but discrete surge activity, and emergence and cancellation of flux in this active region. The movie of these magnetograms revealed two important results that the major opposite polarities of pre-existing region as well as in the emerging flux region (EFR) were approaching towards each other and moving magnetic features (MMF) were ejecting out from the major north polarity at a quasi-periodicity of about ten hrs during 10--13 May 1997. These activities were probably caused by the magnetic reconnection in the lower atmosphere driven by photospheric convergence motions, which were evident in magnetograms. The magnetic field variations such as flux, gradient, and sunspot rotation revealed that free energy was slowly being stored in the corona. The slow low-layer magnetic reconnection may be responsible for this storage and the formation of a sigmoidal core field or a flux rope leading to the eventual eruption. The occurrence of EUV brightenings in the sigmoidal core field prior to the rise of a flux rope suggests that the eruption was triggered by the inner tether-cutting reconnection, but not the external breakout reconnection. An impulsive acceleration revealed from fast separation of the H{\alpha} ribbons of the first 150 seconds suggests the CME accelerated in the inner corona, which is consistent with the temporal profile of the reconnection electric field. In conclusion, we propose a qualitative model in view of framework of a solar eruption involving, mass ejections, filament eruption, CME, and subsequent flare.Comment: 8 figures, accepted for publication in Solar Physic

Transplanckian bremsstrahlung and black hole production

Classical gravitational bremsstrahlung in particle collisions at transplanckian energies is studied in ${\mathcal M}_4\times {\mathcal T}^d$. The radiation efficiency $\epsilon\equiv E_{\rm rad}/E_{\rm initial}$ is computed in terms of the Schwarzschild radius $r_S(\sqrt{s})$, the impact parameter $b$ and the Lorentz factor $\gamma_{\rm cm}$ and found to be $\epsilon=C_d (r_S/b)^{3d+3} \gamma_{\rm cm}^{2d+1}$, larger than previous estimates by many powers of $\gamma_{\rm cm}\gg 1$. The result is reliable for impact parameters in the overlap of $r_S\lambda_C$, with $b_c$ marking (for $d\neq 0$) the loss of the notion of classical trajectories and $\lambda_C\equiv \hbar/mc$ the Compton length of the scattered particles. The condition on $s$ and $m$ for extreme radiation damping and (presumably) no black hole production is also derived.Comment: 4 pages, revtex 4. The discussion section is changed to better clarify the region of validity of our calculation. The physical conclusions and the abstract are modified accordingly. A few more references added. We just added the preprint number CCTP-2010-1

Gravitational wave background from sub-luminous GRBs: prospects for second and third generation detectors

We assess the detection prospects of a gravitational wave background associated with sub-luminous gamma-ray bursts (SL-GRBs). We assume that the central engines of a significant proportion of these bursts are provided by newly born magnetars and consider two plausible GW emission mechanisms. Firstly, the deformation-induced triaxial GW emission from a newly born magnetar. Secondly, the onset of a secular bar-mode instability, associated with the long lived plateau observed in the X-ray afterglows of many gamma-ray bursts (Corsi & Meszaros 2009a). With regards to detectability, we find that the onset of a secular instability is the most optimistic scenario: under the hypothesis that SL-GRBs associated with secularly unstable magnetars occur at a rate of (48; 80)Gpc^{-3}yr^{-1} or greater, cross-correlation of data from two Einstein Telescopes (ETs) could detect the GW background associated to this signal with a signal-to-noise ratio of 3 or greater after 1 year of observation. Assuming neutron star spindown results purely from triaxial GW emissions, we find that rates of around (130;350)Gpc^{-3}yr^{-1} will be required by ET to detect the resulting GW background. We show that a background signal from secular instabilities could potentially mask a primordial GW background signal in the frequency range where ET is most sen- sitive. Finally, we show how accounting for cosmic metallicity evolution can increase the predicted signal-to-noise ratio for background signals associated with SL-GRBs.Comment: Accepted by MNRA

Can stellar mass black holes be quark stars?

We investigate the possibility that stellar mass black holes, with masses in the range of $3.8M_{\odot}$ and $6M_{\odot}$, respectively, could be in fact quark stars in the Color-Flavor-Locked (CFL) phase. Depending on the value of the gap parameter, rapidly rotating CFL quark stars can achieve much higher masses than standard neutron stars, thus making them possible stellar mass black hole candidates. Moreover, quark stars have a very low luminosity and a completely absorbing surface - the infalling matter on the surface of the quark star is converted into quark matter. A possibility of distinguishing CFL quark stars from stellar mass black holes could be through the study of thin accretion disks around rapidly rotating quark stars and Kerr type black holes, respectively. Furthermore, we show that the radiation properties of accretion disks around black holes and CFL quark stars are also very similar. However, strange stars exhibit a low luminosity, but high temperature bremsstrahlung spectrum, which, in combination with the emission properties of the accretion disk, may be the key signature to differentiate massive strange stars from black hole.Comment: 27 pages, 5 figures, accepted for publication in MNRA