369 research outputs found

    Suzaku Detection of Diffuse Hard X-Ray Emission outside Vela X

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    Vela X is a large, 3x2 degrees, radio-emitting pulsar wind nebula (PWN) powered by the Vela pulsar in the Vela supernova remnant. Using four Suzaku/XIS observations pointed just outside Vela X, we find hard X-ray emission extending throughout the fields of view. The hard X-ray spectra are well represented by a power-law. The photon index is measured to be constant at Gamma~2.4, similar to that of the southern outer part of Vela X. The power-law flux decreases with increasing distance from the pulsar. These properties lead us to propose that the hard X-ray emission is associated with the Vela PWN. The larger X-ray extension found in this work strongly suggests that distinct populations relativistic electrons form the X-ray PWN and Vela X, as was recently inferred from multiwavelength spectral modeling of Vela X.Comment: 18 pages, 7 figures, accepted for publication in PASJ (Suzaku Special Issue

    Preserving Operation Frequency Privacy of Incumbents in CBRS

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    Citizens Broadband Radio Service (CBRS) is a novel service band in the United States, spanning 3550-3700 MHz, recently opened for commercial cognitive operations. The CBRS has a three tier hierarchical architecture, wherein, the topmost tier users (also called as incumbents) include military radars. The second and third tier facilitate licensed and unlicensed access to the band, respectively. The privacy of incumbents has been a major concern and different schemes have been proposed in the literature to preserve privacy of their location and operation time. However, the privacy of operation frequency of incumbents has not been suitably addressed. The operation frequency of incumbent is vulnerable to inference attacks from the adversary. For instance, an adversary can deduce the operation frequency of incumbent if a compromised device is asked to switch to another channel. Therefore, in this paper, we propose probabilistic usage of dummy incumbents on a channel and analyse the operation frequency privacy of incumbents for snapshot and time based models in the three tier CBRS system. The optimum dummy generation probability is obtained for the snapshot and time based models, varying capabilities of the adversary, and different system parameters. Finally, we verify the proposed results through simulations. Autho

    A Suzaku Observation of the Low-Ionization Fe-Line Emission from RCW 86

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    The newly operational X-ray satellite Suzaku observed the southwestern quadrant of the supernova remnant (SNR) RCW 86 in February 2006 to study the nature of the 6.4 keV emission line first detected with the Advanced Satellite for Cosmology and Astronomy (ASCA). The new data confirm the existence of the line, localizing it for the first time; most of the line emission is adjacent and interior to the forward shock and not at the locus of the continuum hard emission. We also report the first detection of a 7.1 keV line that we interpret as the K-beta emission from low-ionization iron. The Fe-K line features are consistent with a non-equilibrium plasma of Fe-rich ejecta with n_{e}t <~ 10^9 cm^-3 s and kT_{e} ~ 5 keV. This combination of low n_{e}t and high kT_{e} suggests collisionless electron heating in an SNR shock. The Fe K-alpha line shows evidence for intrinsic broadening, with a width of 47 (34--59) eV (99% error region). The difference of the spatial distributions of the hard continuum above 3 keV and the Fe-K line emission support a synchrotron origin for the hard continuum.Comment: 6 pages with 6 figures. Accepted for PASJ Suzaku Special Issue (vo. 58, sp.1

    Reciprocal regulation of 11β-HSDs may predict steroid sensitivity in childhood nephrotic syndrome

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    Childhood nephrotic syndrome, in which steroid-dependence occurs concurrently with steroid-resistance, requires aggressive therapy to prevent relapse. Predictive biomarkers that can be used to stratify treatment are urgently needed. Here we report that reciprocal regulation of the glucocorticoid metabolizing enzymes, 11β-hydroxysteroid dehydrogenase types 1 and 2, is associated with steroid-responsiveness and disease remission in childhood nephrotic syndrome, potentially providing a marker to identify patients in which aggressive therapy is required.</jats:p

    Transcriptome Analyses of a Salt-Tolerant Cytokinin-Deficient Mutant Reveal Differential Regulation of Salt Stress Response by Cytokinin Deficiency

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    Soil destruction by abiotic environmental conditions, such as high salinity, has resulted in dramatic losses of arable land, giving rise to the need of studying mechanisms of plant adaptation to salt stress aimed at creating salt-tolerant plants. Recently, it has been reported that cytokinins (CKs) regulate plant environmental stress responses through two-component systems. A decrease in endogenous CK levels could enhance salt and drought stress tolerance. Here, we have investigated the global transcriptional change caused by a reduction in endogenous CK content under both normal and salt stress conditions. Ten-day-old Arabidopsis thaliana wild-type (WT) and CK-deficient ipt1,3,5,7 plants were transferred to agar plates containing either 0 mM (control) or 200 mM NaCl and maintained at normal growth conditions for 24 h. Our experimental design allowed us to compare transcriptome changes under four conditions: WT-200 mM vs. WT-0 mM, ipt1,3,5,7-0 mM vs. WT-0 mM, ipt1,3,5,7-200 mM vs. ipt1,3,5,7-0 mM and ipt1,3,5,7-200 mM vs. WT-200 mM NaCl. Our results indicated that the expression of more than 10% of all of the annotated Arabidopsis genes was altered by CK deficiency under either normal or salt stress conditions when compared to WT. We found that upregulated expression of many genes encoding either regulatory proteins, such as NAC, DREB and ZFHD transcription factors and the calcium sensor SOS3, or functional proteins, such as late embryogenesis-abundant proteins, xyloglucan endo-transglycosylases, glycosyltransferases, glycoside hydrolases, defensins and glyoxalase I family proteins, may contribute to improved salt tolerance of CK-deficient plants. We also demonstrated that the downregulation of photosynthesis-related genes and the upregulation of several NAC genes may cause the altered morphological phenotype of CK-deficient plants. This study highlights the impact of CK regulation on the well-known stress-responsive signaling pathways, which regulate plant adaptation to high salinity as well as other environmental stresses

    The synergistic effects of omega-3 fatty acids against 5-fluorouracil-induced mucosal impairment in mice

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    Background: Anti-cancer pharmaceuticals frequently have adverse side effects on patients such as gastrointestinal involvement limiting their clinical applications. These effects may be controlled by nutritional interventions, however, there are few studies that have shown any mechanistic effects. In this study, we examined effects of diet enhanced with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on 5-fluorouracil (5-FU)-induced intestinal impairment and immunity in mice. Methods: C57Bl6 mice were randomized to control diet, control diet + EPA, control + DHA, control + fish oil, or diet enchanced with DHA/EPA. After seven days of each respective diet, mice, excluding those in the sham group, were treated with 10 mg/kg/day 5-FU for 7 days. The effects of 5-FU-induced impairment in the small intestine were assessed using cytokine concentrations in serum and tissue, secretory immunoglobulin (Ig) A, diamine oxidase (DAO) activity, the length of the small intestine, and the expression of apoptosis signaling genes. Results: The EPA/DHA-enhanced diet resulted in the most beneficial, synergystic and protective effect against 5-FU induced weight loss. Protection against inflammation, impaired intestinal function, and immunity of the small intestine were also observed. Individually, a DHA-enriched diet demonstrated a protective effect against 5-FU damage with longer small intestine mucosal and crypt lengths, greater DAO activity, and higher IgA concentrations, whereas the EPA-enriched diet resulted in decreased inflammatory cytokine concentrations in both plasma and small intestine and expression of apoptosis target genes. Conclusions: In conclusion, a diet enhanced with EPA and DHA results in synergism protecting against the detrimental effects of 5-FU and limiting chemotherapy induced mucosal impairment
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