87,187 research outputs found
Irradiation effect of HfO2 MOS structure under gamma-ray
No full textthe effect of gamma irradiation upon Al/HfO2/SiO2/Si MOS structure under different doses of Co-60 is studied in this article as a function of total dosage. MOS capacitors with a stacked gate dielectric of 2.8nm thick SiO2 and 15nm thick HfO2 having electrode areas of 1mm*1mm are prepared on the p-Si substrate using thermal oxidation and atomic layer deposition respectively. The MOS capacitors are under zero bias during irradiation under Co-60 gamma ray with total dose of 100Krad (Si)/500Krad (Si)/1Mrad (Si) and dose rate of 50rad (Si)/s. The high frequency Capacitor-Voltage (C-V) and Current-Voltage (I-V) characteristic of each structure are measured at room temperature before and after irradiation. As well as the C-V and I-V property, Atomic Force Microscopy (AFM), Grazing Incidence X-ray Diffraction (GIXRD), and X-ray Photoelectron Spectroscopy (XPS) are also applied to determine the surface morphology, physical, and mechanical properties before and after different doses of radiation. The oxide trapped charge calculated from the high frequency C-V measurement is in the order of 10(12) cm(-2) and increases linearly with the increase of applied total dose. The XRD spectrum exhibits several phases of SiO2 and HfO2 variation under each total dose. The XPS result shows that each different total dosage leads to the binding energy peak drifting to a different degree demonstrating the influence of irradiation on the valence state of the elements, which can be attributed to the gamma-ray induced interface states
Vacuum birefringence and X-ray polarimetry in transient magnetars
Get PDFRecent optical polarimetry observations of an X-ray dim isolated neutron star, RX J1856.5-3754, showed a first evidence for QED vacuum birefringence induced by a strong magnetic field. This important result can be confirmed by performing systematically polarimetry observations in the X-ray band for other strongly magnetized neutron stars, such as transient or persistent magnetars. We computed the phase averaged polarization fraction (PF) and polarization angle (PA) expected in the thermal emission from transient magnetars in the soft X-ray energy band. We found that the detection of a PF higher than 60% is a strong evidence for vacuum birefringence. We also found that a steady change in the PA measured from transient magnetars during their outburst decay (up to 23 degrees for a magnetospheric untwisting of 0.5 rad) is a strong signature of vacuum birefringence. This latter detection would also provide an independent check of the magnetospheric untwisting model for these sources. Simulations show that these measurements are achievable by future polarimetric missions such as XIPE and IXPE with 20-380 ks of observational time, and with eXTP with 3-60 ks
Discovery of an optical counterpart to the hyperluminous X-ray source in ESO 243-49
No full textThe existence of black holes of masses similar to 10(2)-10(5)M(circle dot) has important implications for the formation and evolution of star clusters and supermassive black holes. One of the strongest candidates to date is the hyperluminous X-ray source (HLX1), possibly located in the S0- a galaxy ESO 243-49, but the lack of an identifiable optical counterpart had hampered its interpretation. Using the Magellan telescope, we have discovered an unresolved optical source with R = 23.80 +/- 0.25 mag and V = 24.5 +/- 0.3 mag within HLX1's positional error circle. This implies an average X-ray/optical flux ratio similar to 500. Taking the same distance as ESO 243-49, we obtain an intrinsic brightness M-R = -11.0 +/- 0.3 mag, comparable to that of a massive globular cluster. Alternatively, the optical source is consistent with a main-sequence M star in the Galactic halo (for example an M4.4 star at approximate to 2.5 kpc). We also examined the properties of ESO 243-49 by combining Swift/Ultraviolet/Optical Telescope (UVOT) observations with stellar population modelling. We found that the overall emission is dominated by a similar to 5-Gyr-old stellar population, but the UV emission at approximate to 2000 angstrom is mostly due to ongoing star formation at a rate of similar to 0.03M(circle dot) yr(-1). The UV emission is more intense (at least a 9 sigma enhancement above the mean) north-east of the nucleus, in the same quadrant as HLX1. With the combined optical and X-ray measurements, we put constraints on the nature of HLX1. We rule out a foreground star and a background AGN. Two alternative scenarios are still viable. HLX1 could be an accreting intermediate mass black hole in a star cluster, which may itself be the stripped nucleus of a dwarf galaxy that passed through ESO 243-49, an event which might have caused the current episode of star formation. Or, it could be a neutron star in the Galactic halo, accreting from an M4-M5 donor star
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Securing XML documents with author-X
No full textAuthor-X is a Java-based system that addresses the security issues of access control and policy design for XML document administration. Author-X supports the specification of policies at varying granularity levels and the specification of user credentials as a way to enforce access control. Access control is available according to both push and pull document distribution policies, and document updates are distributed through a combination of hash functions and digital signature techniques. The Author-X approach to distributed updates allows a user to verify a document's integrity without contacting the document server
Relations between x-ray timing features and spectral parameters of galactic black hole x-ray binaries
Get PDFWe present a study of correlations between spectral and timing parameters for a sample of black hole X-ray binary candidates. Data are taken from GX
339-4, H 1743-322, and XTE J1650-500, as the Rossi X-ray Timing Explorer
(RXTE) observed complete outbursts of these sources. In our study we investigate outbursts that happened before the end of 2009 to make use of the high-energy coverage of the HEXTE detector and select observations that
show a certain type of quasi-periodic oscillations (type-C QPOs). The spectral parameters are derived using the empirical convolution model simpl to model the Comptonized component of the emission together with a disc blackbody for the emission of the accretion disc. Additional spectral features, namely a reflection component, a high-energy cut-off, and excess emission at 6.4 keV, are taken into account. Our investigations confirm the known positive
correlation between photon index and centroid frequency of the QPOs and reveal an anti-correlation between the fraction of up-scattered photons and the QPO frequency. We show that both correlations behave as expected in the “sombrero”
geometry. Furthermore, we find that during outburst decay the correlation between photon index and QPO frequency follow a general track, independent of individual outbursts
X-ray polarization in relativistic jets
No full textWe investigate the polarization properties of Comptonized X-rays from relativistic jets in active galactic nuclei (AGN) using Monte Carlo simulations. We consider three scenarios commonly proposed for the observed X-ray emission in AGN: Compton scattering of blackbody photons emitted from an accretion disc; scattering of cosmic microwave background (CMB) photons and self-Comptonization of intrinsically polarized synchrotron photons emitted by jet electrons. Our simulations show that for Comptonization of disc and CMB photons, the degree of polarization of the scattered photons increases with the viewing inclination angle with respect to the jet axis. In both cases, the maximum linear polarization is ≈20 per cent. In the case of synchrotron self-Comptonization (SSC), we find that the resulting X-ray polarization depends strongly on the seed synchrotron photon injection site, with typical fractional polarizations P≈ 10–20 per cent when synchrotron emission is localized near the jet base, while P≈ 20–70 per cent for the case of uniform emission throughout the jet. These results indicate that X-ray polarimetry may be capable of providing unique clues to identify the location of particle acceleration sites in relativistic jets. In particular, if synchrotron photons are emitted quasi-uniformly throughout a jet, then the observed degree of X-ray polarization may be sufficiently different for each of the competing X-ray emission mechanisms (synchrotron, SSC or external Comptonization) to determine which is the dominant process. However, X-ray polarimetry alone is unlikely to be able to distinguish between disc and CMB Comptonization
Closed reduction with percutaneous Kirschner wire fixation for delayed treatment of distal humeral epiphyseal fracture separation
No full textAbstract
Background: Fracture separation of the distal humeral epiphysis in children is a relatively uncommon injury, predominantly occurring in children under 3 years. It has a high risk of treatment delays. This study aims to evaluate outcomes in the management of fracture separation of the distal humeral epiphysis treated seven or more days postinitial injury.
Methods: A retrospective analysis was conducted on patients diagnosed with fracture separation of the distal humeral epiphysis between November 2016 and October 2023. Inclusion criteria encompassed patients with delayed presentation of fracture separation of the distal humeral epiphysis who underwent surgical intervention seven or more days following the initial injury. Demographic data were collected, and fractures were categorized using the modified DeLee classification. Plain radiographs facilitated the assessment of the carrying angle and postoperative Baumann angle. Clinical outcomes were evaluated using the Flynn criteria.
Results: The study included 12 patients who met the inclusion criteria. The average age at the time of injury was 1.59 years. According to the modified DeLee system, fracture classification identified one type I fracture, eight type II fractures, and three type III fractures. The average duration from injury to surgery was 11.8 days. The mean surgical
duration was 21.5 min. The average follow-up period was 40.7 months. One patient exhibited cubitus varus development. Based on the Flynn criteria, outcomes were as follows: seven patients had excellent outcomes, four had good outcomes, and one had a poor outcome.
Conclusion: Closed reduction with percutaneous K-wire fixation represents a minimally invasive approach suitable for children diagnosed with fracture separation of the distal humeral epiphysis seven or more days post-initial injury. Most of these patients experienced favorable outcomes.
Level of evidenceAbstract
Background: Fracture separation of the distal humeral epiphysis in children is a relatively uncommon injury, predominantly occurring in children under 3 years. It has a high risk of treatment delays. This study aims to evaluate outcomes in the management of fracture separation of the distal humeral epiphysis treated seven or more days postinitial
injury.
Methods: A retrospective analysis was conducted on patients diagnosed with fracture separation of the distal humeral epiphysis between November 2016 and October 2023. Inclusion criteria encompassed patients with delayed presentation of fracture separation of the distal humeral epiphysis who underwent surgical ntervention seven or more days following the initial injury. Demographic data were collected, and fractures were categorized using the modified
DeLee classification. Plain radiographs facilitated the assessment of the carrying angle and postoperative Baumann angle. Clinical outcomes were evaluated using the Flynn criteria.
Results: The study included 12 patients who met the inclusion criteria. The average age at the time of injury was 1.59 years. According to the modified DeLee system, fracture classification identified one type I fracture, eight type II
fractures, and three type III fractures. The average duration from injury to surgery was 11.8 days. The mean surgical duration was 21.5 min. The average follow-up period was 40.7 months. One patient exhibited cubitus varus development. Based on the Flynn criteria, outcomes were as follows: seven patients had excellent outcomes, four had good outcomes, and one had a poor outcome.
Conclusion: Closed reduction with percutaneous K-wire fixation represents a minimally invasive approach suitable for children diagnosed with fracture separation of the distal humeral epiphysis seven or more days post-initial injury. Most of these patients experienced favorable outcomes.
Level of evidence: [AQ: 4
Cidariplura shanmeii Wu & Owada 2013
No full textCidariplura shanmeii Wu & Owada, 2013 (Figs 17, 18, 28, 43, 53) Cidariplura gladiata ab. ochreimacula Strand, 1919: 149, aberration, unavailable infrasubspecific name. Cidariplura gladiata: Wang, 1994: 397; Wang, 2001: 12, nec Butler, 1879. Cidariplura shanmeii Wu & Owada, in Wu et al., 2013: 148, figs 3, 4, 7, 8, part. Type material. Holotype, ♂, Taiwan, Chiayi Co., Shanmei, 800 m, 8. VII. 2011, TFRI128721, S. Wu & W. C. Chang leg. (TFRI) (Fig. 17). Paratypes (8♂ 5♀): Taiwan, the same collecting locality as that of the holotype, 1♂, 5. VIII. 2011, W. C. Chang & S. Wu leg.; the same locality, 1♂, 2. XI. 2011, W. C. Chang & S. Wu leg.; Nantou, Lianhuachi, 600 m, 1♂, 21. V. 2009, C. C. Kuo leg.; the same locality, 1♂, 10. V. 2010, TFRI151527, C. C. Kuo leg.; the same locality, 3♂, 23. VII. 2009, C. C. Kuo leg.; the same locality, 1♂, 12. VII. 2010, C. C. Kuo leg.; 1♂, 10. VIII. 2010, C. C. Kuo leg.; Pingtung, Shouka, 1♀, 450 m, 27. X. 2011, Y. C. Lin leg.; the same locality, 2♀, 22. III. 2012, Y. C. Lin leg.; the same locality, 1♂, 19. VII. 2012, Y. C. Lin leg.; the same locality, 2♀, 15. VIII. 2012, Y. C. Lin leg.; Hualien, Guanfu, 1 ♂, 180 m, 9. VIII. 2010, leg. Y. C. Lin leg.; the same locality, 1♂, 13. IX. 2010, Y. C. Lin leg. (TFRI). Additional material examined. Taiwan. Ilan, Fushan Botanical Garden, 700 m, 1♂, 12, 15–16. VI. 2015, NSMT3305 ♂, M. Owada & S. Wu leg.; the same locality, 2♂ 1♀, 12. V. 2019, NSMT3474 ♂, NSMT3475 ♀, M. Owada & S. Wu leg. (NSMT); Nantou, Lienhuachih [=Lianhuachi], 700 m, 2♂, 17–18. VII. 2012, NSMT3297 ♂ (NSMT), NSMT3300 ♂ (ESRI), M. Owada & L. Shih leg., Huisun Linchang, 770 m, 2♂, 21–22. VI. 2017, NSMT3306 ♂ (NSMT), NSMT3307 ♂ (ESRI), M. Owada & L. Shih leg., Aowanda, 1,000 m, 1♂, 9. V. 2013, NSMT3281 ♂ (NSMT), M. Owada, L. Shih & Y. Chen leg. Notes. Wu et al. (2013) described C. shanmeii with the illustration of the holotype of C. shanmeii, however the illustrated structures in Wu et al. (2013: figs 37, 38, male; 64, female; 69, labial palpus; 80, male foreleg), actually belong to the new species, C. hbun sp. nov., described below. Diagnosis. Externally C. shanmeii and C. hbun are difficult to be separated, but the former species can be distinguished from the latter by the narrowed white forewing discocellular spot, rather than a wider and more yellowish-white spot; the costal process of the valva is digitiform rather than stouter and curved downwards; the distinctively shorter distal portion of valva rather than nearly equal in length as costal process; the digitiform, straight costal process rather than curved ventrally and tapering; the saccular process is extremely small and curved rather than robust and rod-like pointing parallelly with distal portion of valva; the ductus bursae is extremely narrowed compared to the moderate width of other species in the complex. Re-description. Due to the existence of specimens belonging to both C. shanmeii and C. hbun sp. nov. in the paratype series of C. shanmeii (sensu Wu & Owada, in Wu et al., 2013), we re-describe C. shanmeii herein to clarify the identity of that species. Measurements. Forewing length 12–14 mm in males (n= 17); 12–14 mm in females (n= 5). Eye round; antenna ciliate, male with a pair of long bristles on each segment, length of bristle 2 X diameter of shaft in median region. Head, all segments of thorax as well as femur, tibia and 1st tarsal segment chocolate brown. Male labial palpus (Fig. 28) modified as follows: 1st segment very long, upcurved along frons, surpassing vertex, smoothly covered with ordinary scales; 2nd segment bent at a right angle from the 1st, slender, slightly curved, 0. 5 X shorter than 1st, reaching the anterior part of thorax, internally with specialized ochreous scales which are elongated and enlarged at their apices; 3rd segment long, 3 X longer than 2nd, basal part of labial palpus as wide as medial part, internally with long ochreous scales slender and almost twice as long as those in the 2 nd segment. Labial palpus in female: 3 rd shorter than 2 nd, slender, tapering towards apex. Legs: male foretibia with apical spine. Forewing broad, slightly excurved, apex nearly forming right angle; ground coloration chocolate brown; antemedial and postmedial line slender, light ochreous, the former oblique, wave-like, the latter smoothly excurved outward at discal cell part; discocellular spot white, slender and lunate-shaped; submarginal line slender, ochreous, wave-like; outer margin ochreous; marginal scales chocolate brown. Hindwing chocolate brown; medial line ochreous with one ochreous spot situating at outside of tornal area; outer margin ochreous; marginal scales chocolate brown. Abdomen brown, 8th segment unmodified. Male genitalia (Fig. 43)—Uncus broad, stout, apex hook-like. Tegumen and vinculum long, equal in length; saccus V-shaped, medial part elongated anteriorly. Valva trifurcate, costal process, straight and digitiform, distal portion of valva broad, saccular process short, curved and digitiform. Juxta plate-like, transtilla indistinct. Aedeagus stout, straight, 1. 25 X longer than valva; vesica densly scobinate without cornutus. Female genitalia (Fig. 53)—Papillae anales membranous with short hair-like setae; both pairs of apophyses slender, moderate length; ductus bursae as long as corpus bursae, with a pair of slender lateral sclerites. Corpus bursae elliptical, basal half part surrounded by dense internal spinose patch; ductus seminalis arising from lateral base of corpus bursae, broadened and coiled basally. Distribution and phenology. Endemic to Taiwan. The adults occasionally occur from March to November.Published as part of Wu, Shipher, Owada, Mamoru & Wang, Min, 2019, Review of Cidariplura Butler, 1879 (Lepidoptera, Erebidae, Herminiinae). Part 1: the Cidariplura gladiata species complex, pp. 489-502 in Zootaxa 4668 (4) on pages 497-498, DOI: 10.11646/zootaxa.4668.4.3, http://zenodo.org/record/344986
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