X-ray observations have revealed that many microquasars and low-mass X-ray binaries (LMXBs) exhibit narrow absorption features identified with resonant absorption from Fe XXV and Fe XXVI and other ...abundant ions. In many well studied systems there is evidence for blue-shifts, indicating outflowing plasmas. We succesfully model the changes in both the X-ray continuum and the Fe absorption features during dips from all the bright dipping LMXBs observed by XMM-Newton (EXO 0748-676, XB 1254-690, X 1624-490, MXB 1659-298, 4U 1746-371 and XB 1916-053) as resulting primarily from an increase in column density and a decrease in the ionization state of a highly-ionized absorber in a similar way as was done for XB 1323-619. This implies that the complex spectral changes in the X-ray continua observed from the dip sources as a class can be most simply explained primarily by changes in the highly ionized absorbers present in these systems. There is no need to invoke unusual abundances or partial covering of extended emission regions. Outside of the dips, the absorption line properties do not vary strongly with orbital phase. This implies that the ionized plasma has a cylindrical geometry with a maximum column density close to the plane of the accretion disk. Since dipping sources are simply normal LMXBs viewed from close to the orbital plane this implies that ionized plasmas are a common feature of LMXBs.
MAXI J1659−152 is a bright X-ray transient black-hole candidate binary system discovered in September 2010. We report here on MAXI, RXTE, Swift, and XMM-Newton observations during its 2010/2011 ...outburst. We find that during the first one and a half week of the outburst the X-ray light curves display drops in intensity at regular intervals, which we interpret as absorption dips. About three weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414 ± 0.005 h, which we interpret as the orbital period of the system. This implies that MAXI J1659−152 is the shortest period black-hole candidate binary known to date. The inclination of the accretion disk with respect to the line of sight is estimated to be 65–80°. We propose the companion to the black-hole candidate to be close to an M5 dwarf star, with a mass and radius of about 0.15–0.25 M⊙ and 0.2–0.25 R⊙, respectively. We derive that the companion had an initial mass of about 1.5 M⊙, which evolved to its current mass in about 5–6 billion years. The system is rather compact (orbital separation of ≳1.33 R⊙), and is located at a distance of 8.6 ± 3.7 kpc, with a height above the Galactic plane of 2.4 ± 1.0 kpc. The characteristics of short orbital period and high Galactic scale height are shared with two other transient black-hole candidate X-ray binaries, i.e., XTE J1118+480 and Swift J1735.5−0127. We suggest that all three are kicked out of the Galactic plane into the halo, rather than being formed in a globular cluster.
Context.During the first year in operation, INTEGRAL, the European Space Agency's γ-ray observatory, has detected more than 28 new bright sources in the galactic plane which emit the bulk of their ...emission above 10 keV. Aims.To understand the nature of those sources we have obtained follow-up observations in the X-ray band with XMM-Newton. Methods.We derive accurate X-ray positions, propose infrared counterparts and study the source high energy long and short term variability and spectra. Results.70% of the sources are strongly absorbed ($N_{\rm H}\geq10^{23}$ atom cm-2). More than half of these absorbed sources show pulsations with periods ranging from 139 to 1300 s, i.e., they are slow X-ray pulsars. The candidate infrared counterparts are not as strongly absorbed demonstrating that part of the absorbing matter is local to the sources. Conclusions.Many of these new sources are supergiant high-mass X-ray binaries (HMXB) in which the stellar wind of the companion star is accreted onto the compact object. The large local absorption in these new sources can be understood if the compact objects are buried deep in their stellar winds. These new objects represent half of the population of supergiant HMXB.
We report the detection of narrow $\ion{Fe}{xxv}$ and $\ion{Fe}{xxvi}$ X-ray absorption lines at $6.68 \pm 0.04$ keV and $6.97 \pm 0.05$ keV in the persistent emission of the dipping low-mass X-ray ...binary 4U 1323-62 during a 2003 January XMM-Newton observation. These features are superposed on a broad emission feature centered on $6.6\,^{+0.1}_{-0.2}$ keV. During dipping intervals the equivalent width of the $\ion{Fe}{xxv}$ feature increases while that of the $\ion{Fe}{xxvi}$ feature decreases, consistent with the presence of less strongly ionized material in the line-of-sight. As observed previously, the changes in the 1.0–10 keV spectrum during dips are inconsistent with a simple increase in absorption by cool material. However, the changes in both the absorption features and the continuum can be modeled by variations in the properties of an ionized absorber. No partial covering of any component of the spectrum, and hence no extended corona, are required. From persistent to deep dipping, the photo-ionization parameter, ξ, expressed in , decreases from $\log(\xi)$ of $3.9 \pm 0.1$ to $\log(\xi)$ of $3.13 \pm 0.07$, while the equivalent hydrogen column density of the ionized absorber increases from ($3.8 \pm 0.4$) $\times~$1022 atoms cm-2 to ($37 \pm 2$) $\times~$1022 atoms cm-2. Since highly-ionized absorption features are seen from many other dip sources, this mechanism may also explain the overall changes in X-ray spectrum observed during dipping intervals from these systems.
Anticitrullinated protein antibody (ACPA)+ individuals with non-specific musculoskeletal symptoms are at risk of inflammatory arthritis (IA). This study aims to demonstrate the predictive value of T ...cell subset quantification for progression towards IA and compare it with previously identified clinical predictors of progression.
103 ACPA+ individuals without clinical synovitis were observed 3-monthly for 12 months and then as clinically indicated. The end point was the development of IA. Naïve, regulatory T cells (Treg) and inflammation related cells (IRCs) were quantified by flow cytometry. Areas under the ROC curve (AUC) were calculated. Adjusted logistic regressions and Cox proportional hazards models for time to progression to IA were constructed.
Compared with healthy controls (age adjusted where appropriate), ACPA+ individuals demonstrated reduced naïve (22.1% of subjects) and Treg (35.8%) frequencies and elevated IRC (29.5%). Of the 103 subjects, 48(46.6%) progressed. Individually, T cell subsets were weakly predictive (AUC between 0.63 and 0.66), although the presence of 2 T cell abnormalities had high specificity. Three models were compared: model-1 used T cell subsets only, model-2 used previously published clinical parameters, model-3 combined clinical data and T cell data. Model-3 performed the best (AUC 0.79 (95% CI 0.70 to 0.89)) compared with model-1 (0.75 (0.65 to 0.86)) and particularly with model-2 (0.62 (0.54 to 0.76)) demonstrating the added value of T cell subsets. Time to progression differed significantly between high-risk, moderate-risk and low-risk groups from model-3 (p=0.001, median 15.4 months, 25.8 months and 63.4 months, respectively).
T cell subset dysregulation in ACPA+ individuals predates the onset of IA, predicts the risk and faster progression to IA, with added value over previously published clinical predictors of progression.
Autophagy is a conserved biological stress response in mammalian cells that is responsible for clearing damaged proteins and organelles from the cytoplasm and recycling their contents via the ...lysosomal pathway. In cases of mild stress, autophagy acts as a survival mechanism, while in cases of severe stress cells may switch to programmed cell death. Understanding the decision process that moves a cell from autophagy to apoptosis is important since abnormal regulation of autophagy occurs in many diseases, including cancer. To integrate existing knowledge about this decision process into a rigorous, analytical framework, we built a mathematical model of cell fate decisions mediated by autophagy. Our dynamical model is consistent with existing quantitative measurements of autophagy and apoptosis in rat kidney proximal tubular cells responding to cisplatin‐induced stress.
We analysed data from five XMM-Newton observations of GX 13 + 1 to investigate the variability of the photo-ionised absorber in this source. We fitted EPIC and RGS spectra obtained from the ...“least-variable” intervals with a model consisting of disc-blackbody and blackbody components together with a Gaussian emission feature at ~6.55–6.7 keV modified by absorption due to cold and photo-ionised material. We found a significant correlation between the hard, ~6–10 keV, flux, the ionisation and column density of the absorber and the equivalent width of the broad iron line. We interpret the correlation in a scenario in which a disc wind is thermally driven at large, ~1010 cm, radii and the broad line results from reprocessed emission in the wind and/or hot atmosphere. The breadth of the emission line is naturally explained by a combination of scattering, recombination and fluorescence processes. We attribute the variations in the absorption and emission along the orbital period to the view of different parts of the wind, possibly located at slightly different inclination angles. We constrain the inclination of GX 13 + 1 to be between 60 and 80° from the strong absorption in the line of sight, which obscures up to 80% of the total emission in one observation, and the absence of eclipses. We conclude that either a disc wind and/or a hot atmosphere can explain the current observations of narrow absorption and broad iron emission features in neutron star low-mass X-ray binaries as a class.
Patient and public involvement and engagement (PPIE) is essential for improved research outcomes and reduced research waste. To be effective, PPIE should provide opportunities for diverse groups to ...contribute to all research stages. However, UK ethnic minority communities remain underrepresented in research. This article describes strategies adopted in a public health research project that were effective in building trust and increasing inclusion of ethnic minority communities. The study team of researchers and PPIE partners reflects lessons learnt during the project and describe six main strategies that built meaningful levels of trust and inclusion: 1) early start to recruitment of PPIE partners; 2) relationship-focused engagement; 3) co-production and consultation activities; 4) open communication and iterative feedback; 5) co-production of project closure activities, and; 6) diverse research team. Meaningful outcomes for the community included the involvement of people from ethnic minorities as research participants and PPIE partners, community wellbeing, co-production of public health recommendations co-presented at the UK Houses of Parliament, and consortium-wide impact evidenced by the enrolment of 51 active PPIE partners. PPIE partners reflect on their research involvement, offering advice to researchers and encouraging people from ethnic minority communities to take part in research. An important message from PPIE partners is that involvement should not be restricted to projects specific to ethnic minorities but become a routine part of general population research, recognising ethnic minorities as an integral part of UK society. In conclusion, this article demonstrates that with appropriate strategies, inclusion and diversity can be achieved in public health research. We recommend researchers, practitioners and policy makers adopt these strategies when planning their public health projects.
We report on two new XMM–Newton observations of the anomalous X-ray pulsar (AXP) 4U 0142+614 performed in 2004 March and July, collecting the most accurate spectrum for this source. Furthermore, we ...analyse two short archival observations performed in 2002 February and 2003 January in order to study the long-term behaviour of this AXP. 4U 0142+614 appears to be relatively steady in flux between 2002 and 2004, and the phase-averaged spectrum does not show any significant variability between the four epochs. We derive the deepest upper limits to date on the presence of lines in 4U 0142+614 spectrum as a function of energy: equivalent width in the 1–3 keV energy range <4 and <8 eV for narrow and broad lines, respectively. A remarkable energy dependence in both the pulse profile and the pulsed fraction is detected, and consequently pulse–phase spectroscopy shows spectral variability as a function of phase. By making use of XMM–Newton and INTEGRAL data, we successfully model the 1–250 keV spectrum of 4U 0142+614 with three models, namely the canonical absorbed blackbody plus two power laws, a resonant cyclotron scattering model plus one power-law and two log-parabolic functions.
Heat transfer coefficients have been measured for phosphor bronze spheres freely moving around a bed of hot sand fluidised by air. The experiments involved inserting such a sphere (diam. 2–
8
mm
) ...attached to a very thin (o.d.
0.2
mm
), flexible, light thermocouple into an electrically heated fluidised bed of sand, held at
750°
C,
825°
C
or 900°C. Measurements were made of the rate at which the phosphor bronze sphere was heated up for various fluidising velocities, sizes of sand,
etc. The heat transfer coefficient was measured in such a way as to exclude any contribution from radiation, which was established as operating quite independently of the fluidising conditions. The heat transfer coefficient due solely to convection and conduction was found to increase only slightly with the temperature of the bed; also there were small decreases when
U/
U
mf
was increased. However, there were significant decreases in heat transfer coefficient when the size of the sand particles was increased; in addition, the heat transfer coefficient was slightly smaller for larger phosphor bronze spheres. A model was developed to predict such heat transfer coefficients; the dominant contribution usually turns out to be heat transfer from the hot sand particles to the immersed sphere, with heat transfer from the fluidising gas being less important. The model predicted heat transfer coefficients in tolerably good agreement with the values measured. However, the heat transfer coefficients measured here are somewhat lower than the differing values obtained by previous workers; also they do not depend on the fraction of the fluidised bed occupied by bubbles. Furthermore, the coefficient for heat transfer from the fluidised particles to the phosphor bronze sphere does not depend on the diameter of that sphere. This contrasts with heat transfer from the fluidising gas, for which the heat transfer coefficient decreases, when the diameter of the phosphor bronze sphere is increased.
PDF
