450 research outputs found

    A spectral-timing model for ULXs in the supercritical regime

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    Ultraluminous X-ray sources (ULXs) with luminosities lying between ∼3 × 1039 and 2 × 1040 erg s−1 represent a contentious sample of objects as their brightness, together with a lack of unambiguous mass estimates for the vast majority of the central objects, leads to a degenerate scenario where the accretor could be a stellar remnant (black hole or neutron star) or intermediate-mass black hole (IMBH). Recent, high-quality observations imply that the presence of IMBHs in the majority of these objects is unlikely unless the accretion flow somehow deviates strongly from expectation based on objects with known masses. On the other hand, physically motivated models for supercritical inflows can re-create the observed X-ray spectra and their evolution, although have been lacking a robust explanation for their variability properties. In this paper, we include the effect of a partially inhomogeneous wind that imprints variability on to the X-ray emission via two distinct methods. The model is heavily dependent on both inclination to the line of sight and mass accretion rate, resulting in a series of qualitative and semiquantitative predictions. We study the time-averaged spectra and variability of a sample of well-observed ULXs, finding that the source behaviours can be explained by our model in both individual cases as well as across the entire sample, specifically in the trend of hardness-variability power. We present the covariance spectra for these sources for the first time, which shed light on the correlated variability and issues associated with modelling broad ULX spectra

    High coercivity, anisotropic, heavy rare earth-free Nd-Fe-B by Flash Spark Plasma Sintering

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    The authors wish to extend their gratitude to neo Magnequench for providing the materials used in this study. The research was supported by EU-FP7 MAG-DRIVE project (No. 605348) [http://www.mag-drive-fp7.eu/]. MJR and SG would like to acknowledge the EPSRC Programme Grant XMAT [EP/K008749/2]

    A new, clean catalogue of extragalactic non-nuclear X-ray sources in nearby galaxies

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    We have created a new, clean catalogue of extragalactic non-nuclear X-ray sources by correlating the 3XMM-DR4 data release of the XMM-Newton Serendipitous Source Catalogue with the Third Reference Catalogue of Bright Galaxies and the Catalogue of Neighbouring Galaxies, using an improved version of the method presented in Walton et al. Our catalogue contains 1314 sources, of which 384 are candidate ultraluminous X-ray sources (ULXs). The resulting catalogue improves upon previous catalogues in its handling of spurious detections by taking into account XMM-Newton quality flags. We estimate the contamination of ULXs by background sources to be 24 per cent. We define a 'complete' subsample as those ULXs in galaxies for which the sensitivity limit is below 10 39 erg s -1 and use it to examine the hardness ratio properties between ULX and non-ULX sources, and ULXs in different classes of host galaxy. We find that ULXs have a similar hardness ratio distribution to lower luminosity sources, consistent with previous studies. We also find that ULXs in spiral and elliptical host galaxies have similar distributions to each other independent of host galaxy morphology, however, our results do support previous indications that the population of ULXs is more luminous in star-forming host galaxies than in non-star-forming galaxies. Our catalogue contains further interesting subpopulations for future study, including Eddington Threshold sources and highly variable ULXs. We also examine the highest luminosity (L X > 5 × 10 40 erg s -1) ULXs in our catalogue in search of intermediate-mass black hole candidates, and find nine new possible candidates.We gratefully acknowledge support from the Science and Technology Facilities Council (HPE through grant ST/K501979/1, TPR through ST/P000541/1). HPE acknowledges support under National Aeronautics and Space Administration contract NNG08FD60C. MJM and DJW acknowledge support from STFC Ernest Rutherford fellowships. SM acknowledges financial support by the Spanish Ministry of Economy and Competitiveness through grant AYA2016-76730-P (MINECO/FEDER)

    Vibration transmissibility measurement of glove materials under different grip forces

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    The transmission of vibration from tools, through work gloves and into the hands, is affected by many factors such as glove material properties, tool vibration conditions, temperature, and grip force. This study investigated how glove material properties affect tool vibration transmission into the index finger. Three samples of material (two taken from differently designed anti-vibration gloves and another for comparison that was designed for mounting vibration-sensitive equipment) were assessed using stepped sinusoidal vertical vibration excitations covering a range of a one-third octave band (from 20 to 400 Hz). Twelve human subjects were used for the testing. For all samples and subjects, measurements were obtained for: (I) dynamic mechanical analysis (DMA) of the samples; (II) the transmissibility of vibration to the index finger at a grip force of 30 N, across the range of frequencies; and (III) transmissibility of vibration to the index finger at a frequency of 125 Hz for finger grip forces of 15, 30, and 45 N. No significant vibration attenuation was provided at frequencies below 150 Hz. The two materials taken from the gloves that passed the ISO 10819:1996 test showed resonance at frequencies of 150 and 160 Hz a, but the material that did not pass the ISO test showed resonance at 250 Hz. The attenuation for all three materials was occurred at 400 Hz. There was no significant change of transmissibility across the range of finger grip forces for any of the material samples. The level of transmissibility was found to vary between samples and subjects

    Fantastic plastic? Experimental evaluation of polyurethane bone substitutes as proxies for human bone in trauma simulations

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    Recent years have seen steady improvements in the recognition and interpretation of violence related injuries in human skeletal remains. Such work has at times benefited from the involvement of biological anthropologists in forensic casework and has often relied upon comparison of documented examples with trauma observed in skeletal remains. In cases where no such example exists investigators must turn to experimentation. The selection of experimental samples is problematic as animal proxies may be too dissimilar to humans and human cadavers may be undesirable for a raft of reasons. The current article examines a third alternative in the form of polyurethane plates and spheres marketed as viable proxies for human bone in ballistic experiments. Through subjecting these samples to a range of impacts from both modern and archaic missile weapons it was established that such material generally responds similarly to bone on a broad, macroscopic scale but when examined in closer detail exhibits a range of dissimilarities that call for caution in extrapolating such results to real bone

    ‘Choicest unguents’: molecular evidence for the use of resinous plant exudates in late Roman mortuary rites in Britain

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    YesResinous substances were highly prized in the ancient world for use in ritual contexts. Details gleaned from classical literature indicate that they played a significant role in Roman mortuary rites, in treatment of the body and as offerings at the tomb. Outside of Egypt, however, where research has shown that a range of plant exudates were applied as part of the mummification process, resins have rarely been identified in the burial record. This is despite considerable speculation regarding their use across the Roman Empire. Focusing on one region, we investigated organic residues from forty-nine late Roman inhumations from Britain. Using gas chromatographyemass spectrometry and the well-attested biomarker approach, terpenic compounds were characterized in fourteen of the burials analysed. These results provided direct chemical evidence for the presence of exudates from three different plant families: coniferous Pinaceae resins, Mediterranean Pistacia spp. resins (mastic/terebinth) and exotic Boswellia spp. gum-resins (frankincense/olibanum) from southern Arabia or beyond. The individuals accorded this rite had all been interred with a package of procedures more elaborate than the norm. These findings illuminate the multiplicity of roles played by resinous substances in Roman mortuary practices in acting to disguise the odour of decomposition, aiding temporary soft-tissue preservation and signifying the social status of the deceased. Nevertheless, it was their ritual function in facilitating the transition to the next world that necessitated transportation to the most remote outpost of the late Roman Empire, Britain.R.C.B is supported by a PhD studentship from the Art and Humanities Research Council (43019R00209)

    A review of issues affecting the efficiency of decision making in the NICE single technology appraisal process

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    BACKGROUND: Escalating demands upon the National Institute for Health and Care Excellence's (NICE's) Single Technology Appraisal (STA) programme require a 2.5-times increase upon 2015 capacity by 2020. This additional strain on committee resources threatens to compromise the rigour of the STA process. In 2018, NICE introduced changes to the appraisal process, aiming to expedite final decisions, including consultation opportunities prior to the company's evidence submission, a 'Technical Engagement' stage prior to the first committee meeting, and powers for committee chairs to recommend technologies without a second formal meeting. OBJECTIVE: This study reviews recent STAs and aims to understand why appraisals require multiple meetings, and whether recent reforms can address the underlying issues. METHODS: NICE STAs published between January 2010 and January 2018 were reviewed, excluding updates or re-considerations. Data on cost, clinical, and decision-making outcomes from 146 appraisals were extracted and analysed thematically. RESULTS: Drugs for advanced cancers were least likely to be recommended (28/43 [65.1%] vs 71/74 [96%] for non-cancer) and took longer (2.36 meetings for a final decision vs 1.97 for non-cancer). The academic review increased upon the company's base-case incremental cost-effectiveness ratio by a median of 32.7%. Eighty-four technologies (57.5%) received a negative preliminary recommendation, deferring a final decision by an average of 142 days. Of these, 85.1% were not considered cost-effective. Uncertainty in economic (34.3%) and clinical (22.3%) data also prevented a positive decision. The majority (72.6% [61/84]) of negative preliminary decisions were overturned following further committee discussion; important considerations were Patient Access Schemes, decision optimisation, and the Cancer Drugs Fund. CONCLUSIONS: Value considerations are the primary driver of negative preliminary recommendations. It is unclear if new opportunities for additional interaction between NICE, review groups, and manufacturers will meaningfully improve the efficiency of the appraisal process, particularly given the proportion of technologies requiring further committee discussion for decision optimisation or admission into the CDF

    Analysis of the National Adult Nutrition Survey (Ireland) and the Food4Me Nutrition Survey Databases to Explore the Development of Food Labelling Portion Sizes for the European Union

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    The present study set out to explore the option of developing food portion size for nutritional labelling purposes using two European Union (EU) dietary surveys. The surveys were selected as they differed in (a) methodologies (food diary versus food frequency questionnaire), (b) populations (Irish National Adult Nutrition Survey (NANS) versus a seven-country survey based on the pan EU study Food4Me), (c) food quantification (multiple options versus solely photographic album) and (d) duration (4 consecutive days versus recent month). Using data from these studies, portion size was determined for 15 test foods, where portion size was defined as the median intake of a target food when consumed. The median values of the portion sizes derived from both the NANS and Food4Me surveys were correlated (r = 0.823; p < 0.00) and the mean of the two survey data sets were compared to US values from the Recognized as Customarily Consumed (RACC) database. There was very strong agreement across all food categories between the averaged EU and the US portion size (r = 0.947; p < 0.00). It is concluded that notwithstanding the variety of approaches used for dietary survey data in the EU, the present data supports using a standardized approach to food portion size quantification for food labelling in the EU

    Epigenomics of being bullied: changes in DNA methylation following bullying exposure

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    Bullying among children is ubiquitous and associated with pervasive mental health problems. However, little is known about the biological pathways that change after exposure to bullying. Epigenome-wide changes in DNA methylation in peripheral blood were studied from pre- to post measurement of bullying exposure, in a longitudinal study of the population-based Generation R Study and Avon Longitudinal Study of Parents and Children (combined n = 1,352). Linear mixed-model results were meta-analysed to estimate how DNA methylation changed as a function of exposure to bullying. Sensitivity analyses including co-occurring child characteristics and risks were performed, as well as a Gene Ontology analysis. A candidate follow-up was employed for CpG (cytosine-phosphate-guanine) sites annotated to 5-HTT and NR3C1. One site, cg17312179, showed small changes in DNA methylation associated to bullying exposure (b = −2.67e-03, SE = 4.97e-04, p = 7.17e-08). This site is annotated to RAB14, an oncogene related to Golgi apparatus functioning, and its methylation levels decreased for exposed but increased for non-exposed. This result was consistent across sensitivity analyses. Enriched Gene Ontology pathways for differentially methylated sites included cardiac function and neurodevelopmental processes. Top CpG sites tended to have overall low levels of DNA methylation, decreasing in exposed, increasing in non-exposed individuals. There were no gene-wide corrected findings for 5-HTT and NR3C1. This is the first study to identify changes in DNA methylation associated with bullying exposure at the epigenome-wide significance level. Consistent with other population-based studies, we do not find evidence for strong associations between bullying exposure and DNA methylation

    A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by Swift

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    We report the detection of a 78.1 ± 0.5 day period in the X-ray light curve of the extreme ultraluminous X-ray source NGC 5907 ULX1 (LX,peak∼5×1040{L}_{{\rm{X,peak}}}\sim 5\times {10}^{40} erg s−1), discovered during an extensive monitoring program with Swift. These periodic variations are strong, with the observed flux changing by a factor of ~3–4 between the peaks and the troughs of the cycle; our simulations suggest that the observed periodicity is detected comfortably in excess of 3σ significance. We discuss possible origins for this X-ray period, but conclude that at the current time we cannot robustly distinguish between orbital and super-orbital variations
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