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An observation of Mrk 478 using the Chandra Low Energy Transmission GratingSpectrometer is presented. The source exhibited 30-40% flux variations ontimescales of order 10000 s together with a slow decline in the spectralsoftness over the full 80 ks observation. The 0.15--3.0 keV spectrum is wellfitted by a single power law with photon index of Gamma = 2.91 +/- 0.03.Combined with high energy data from BeppoSAX, the spectrum from 0.15 to 10 keVis well fit as the sum of two power laws with Gamma = 3.03 +/- 0.04, whichdominates below 2 keV and 1.4 +/- 0.2, which dominates above 2 keV (quoting 90%confidence uncertainties). No significant emission or absorption features aredetected in the high resolution spectrum, supporting our previous findingsusing the Extreme Ultraviolet Explorer but contradicting the claims of emissionlines by Hwang & Bowyer (1997). There is no evidence of a warm absorber, asfound in the high resolution spectra of many Sy 1 galaxies including othersclassified as narrow line Sy 1 galaxies such as Mrk 478. We suggest that theX-ray continuum may result from Comptonization of disk thermal emission in ahot corona through a range of optical depths.

There has been an increase in the availability and utilization of commercially available 3D printers in radiotherapy, with applications in phantoms, brachytherapy applicators, bolus, compensators, and immobilization devices. Additive manufacturing in the form of 3D printing has the advantage of rapid production of personalized patient specific prints or customized phantoms within a short timeframe. One of the barriers to uptake has been the lack of guidance. The aim of this Topical Review is to present the Radiotherapy applications and provide guidance on important areas for establishing a 3D printing Service in a Radiotherapy Department including procurement, commissioning, material selection, establishment of relevant quality assurance (QA), multidisciplinary team creation and training., (© 2025 Institute of Physics and Engineering in Medicine. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

The centre of the Milky Way Galaxy hosts a black hole with a solar mass of about 4 million (Sagittarius A * (Sgr A)) that is very quiescent at present with a luminosity many orders of magnitude below those of active galactic nuclei 1 . Reflection of X-rays from Sgr A * by dense gas in the Galactic Centre region offers a means to study its past flaring activity on timescales of hundreds and thousands of years 2 . The shape of the X-ray continuum and the strong fluorescent iron line observed from giant molecular clouds in the vicinity of Sgr A * are consistent with the reflection scenario 3-5 . If this interpretation is correct, the reflected continuum emission should be polarized 6 . Here we report observations of polarized X-ray emission in the direction of the molecular clouds in the Galactic Centre using the Imaging X-ray Polarimetry Explorer. We measure a polarization degree of 31% ± 11%, and a polarization angle of -48° ± 11°. The polarization angle is consistent with Sgr A * being the primary source of the emission, and the polarization degree implies that some 200 years ago, the X-ray luminosity of Sgr A * was briefly comparable to that of a Seyfert galaxy., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Pulsar wind nebulae are formed when outflows of relativistic electrons and positrons hit the surrounding supernova remnant or interstellar medium at a shock front. The Vela pulsar wind nebula is powered by a young pulsar (B0833-45, aged 11,000 years) 1 and located inside an extended structure called Vela X, which is itself inside the supernova remnant 2 . Previous X-ray observations revealed two prominent arcs that are bisected by a jet and counter jet 3,4 . Radio maps have shown high linear polarization of 60% in the outer regions of the nebula 5 . Here we report an X-ray observation of the inner part of the nebula, where polarization can exceed 60% at the leading edge-approaching the theoretical limit of what can be produced by synchrotron emission. We infer that, in contrast with the case of the supernova remnant, the electrons in the pulsar wind nebula are accelerated with little or no turbulence in a highly uniform magnetic field., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Magnetars are neutron stars with ultrastrong magnetic fields, which can be observed in x-rays. Polarization measurements could provide information on their magnetic fields and surface properties. We observed polarized x-rays from the magnetar 4U 0142+61 using the Imaging X-ray Polarimetry Explorer and found a linear polarization degree of 13.5 ± 0.8% averaged over the 2- to 8-kilo-electron volt band. The polarization changes with energy: The degree is 15.0 ± 1.0% at 2 to 4 kilo-electron volts, drops below the instrumental sensitivity ~4 to 5 kilo-electron volts, and rises to 35.2 ± 7.1% at 5.5 to 8 kilo-electron volts. The polarization angle also changes by 90° at ~4 to 5 kilo-electron volts. These results are consistent with a model in which thermal radiation from the magnetar surface is reprocessed by scattering off charged particles in the magnetosphere.

A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a polarimetric observation of the XRB Cygnus X-1 using the Imaging X-ray Polarimetry Explorer. The electric field position angle aligns with the outflowing jet, indicating that the jet is launched from the inner x-ray-emitting region. The polarization degree is 4.01 ± 0.20% at 2 to 8 kiloelectronvolts, implying that the accretion disk is viewed closer to edge-on than the binary orbit. These observations reveal that hot x-ray-emitting plasma is spatially extended in a plane perpendicular to, not parallel to, the jet axis.

Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to around 1 TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets. Measurements of the radio to optical polarization-the only range available until now-probe extended regions of the jet containing particles that left the acceleration site days to years earlier 1-3 , and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian 501 (Mrk 501). We measure an X-ray linear polarization degree Π X of around 10%, which is a factor of around 2 higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration and also implies that the plasma becomes increasingly turbulent with distance from the shock., (© 2022. The Author(s).)

Astronomical imaging with micro-arcsecond (µas) angular resolution could enable breakthrough scientific discoveries. Previously proposed µas x-ray imager designs have been interferometers with limited effective collecting area. Here we describe x-ray telescopes achieving diffraction-limited performance over a wide energy band with large effective area, employing a nested-shell architecture with grazing-incidence mirrors, while matching the optical path lengths between all shells. We present two compact nested-shell Wolter Type 2 grazing-incidence telescope designs for diffraction-limited x-ray imaging: a micro-arcsecond telescope design with 14 µas angular resolution and 2.9 m 2 of effective area at 5 keV photon energy ( λ =0.25 n m ), and a smaller milli-arcsecond telescope design with 525 µas resolution and 645 c m 2 effective area at 1 keV ( λ =1.24 n m ). We describe how to match the optical path lengths between all shells in a compact mirror assembly and investigate chromatic and off-axis aberrations. Chromatic aberration results from total external reflection off of mirror surfaces, and we greatly mitigate its effects by slightly adjusting the path lengths in each mirror shell. The mirror surface height error and alignment requirements for diffraction-limited performance are challenging but arguably achievable in the coming decades. Because the focal ratio for a diffraction-limited x-ray telescope is extremely large ( f / D ∼10 5 ), the only important off-axis aberration is curvature of field, so a 1 arc sec field of view is feasible with a flat detector. The detector must fly in formation with the mirror assembly, but relative positioning tolerances are on the order of 1 m over a distance of some tens to hundreds of kilometers. Although there are many challenges to achieving diffraction-limited x-ray imaging, we did not find any fundamental barriers.

Background & Aims: Currently, staging of fibrosis in preclinical rodent liver fibrosis models is achieved histologically. Many animals are used at multiple time-points to assess disease progression or therapeutic responses. Hepatic myofibroblasts promote liver fibrosis therefore quantifying these cells in vivo could assess disease or predict therapeutic responses in mice. We fluorescently labelled a single chain antibody (C1-3) that binds hepatic myofibroblasts to monitor fibrogenesis in vivo., Methods: CCl4 was used to induce acute liver injury in WT and cRel(-/-) mice. Bile duct ligation was used to model chronic fibrosis. Hepatic myofibroblasts were depleted using a liposome-drug delivery system or chemically with sulfasalazine. An IVIS® spectrum visualised fluorophore-conjugated C1-3 in vivo., Results: IVIS detection of fluorescently labelled-C1-3 but not a control antibody discriminates between fibrotic and non-fibrotic liver in acute and chronic liver fibrosis models. cRel(-/-) mice have a fibro-protective phenotype and IVIS signal is reduced in CCl4 injured cRel(-/-) mice compared to wild-type. In vivo imaging of fluorescently labelled-C1-3 successfully predicts reductions in hepatic myofibroblast numbers in fibrotic liver disease in response to therapy., Conclusions: We report a novel fluorescence imaging method to assess murine hepatic myofibroblast numbers in vivo during liver fibrosis and after therapy. We also describe a novel liposomal antibody targeting system to selectively deliver drugs to hepatic myofibroblasts in vivo. C1-3 binds human hepatic myofibroblast therefore imaging labelled-C1-3 could be used for clinical studies in man to help stage fibrosis, demonstrate efficacy of drugs that promote hepatic myofibroblast clearance or predict early therapeutic responses., Lay Summary: In response to damage and injury scars develop in the liver and the main cell that makes the scar tissue is the hepatic myofibroblast (HM). C1-3 is an antibody fragment that binds to the scar forming HM. We have fluorescently labelled C1-3 and given it to mice that have either normal or scarred livers (which contain HM) and then used a machine called an in vivo imaging system (IVIS) that takes pictures of different wavelengths of light, to visualise the antibody binding to HM inside the living mouse. Using fluorescently labelled C1-3 we can assess HM numbers in the injured liver and monitor response to therapy. We have also used C1-3 to target drugs encapsulated in lipid carriers (liposomes) to the HM to kill the HM and reduce the liver disease., (Copyright © 2016 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Objective: Relative contributions of reversible β-cell dysfunction and true decrease in β-cell mass in type 2 diabetes remain unclear. Definitive rodent lineage-tracing studies have identified β-cell dedifferentiation and subsequent reprogramming to α-cell fate as a novel mechanism underlying β-cell failure. The aim was to determine whether phenotypes of β-cell dedifferentiation and plasticity are present in human diabetes., Research Design and Methods: Immunofluorescence colocalization studies using classical endocrine and mesenchymal phenotypic markers were undertaken using pancreatic sections and isolated islets from three individuals with diabetes and five nondiabetic control subjects., Results: Intraislet cytoplasmic coexpression of insulin and vimentin, insulin and glucagon, and vimentin and glucagon were demonstrated in all cases. These phenotypes were not present in nondiabetic control subjects., Conclusions: Coexpression of mesenchymal and α-cell phenotypic markers in human diabetic islet β-cells has been confirmed, providing circumstantial evidence for β-cell dedifferentiation and possible reprogramming to α-cells in clinical diabetes.

Social work has struggled with image problems and misperceptions of the profession and the types of services it provides. Photography is a medium that has been used effectively by other professions to change attitudes and perceptions. The present study examined the potential of photographs to change the image of available social services--namely, an adult day care program. Participants were divided into two groups: (1) a control group that only completed a survey on attitudes about adult day care services and (2) an experimental group that viewed photographs showing positive images of clients engaged in program activities before taking the survey. A multivariate regression demonstrated that those who saw the photographs before taking the survey had more positive attitudes about adult day care services. In fact, the variable representing the presentation of the photographs had the strongest effect on attitudes. Such findings suggest that photography is a potentially powerful tool to promote positive attitudes about social services programs. The implications of these results are discussed.

The relationship between bile duct damage and portal fibrosis in chronic liver diseases remains unclear. This study was designed to show whether human intrahepatic biliary epithelial cells can undergo epithelial-mesenchymal cell transition, thereby directly contributing to fibrogenesis. Primary human cholangiocytes were stimulated with transforming growth factor-beta (TGFbeta) or TGFbeta-presenting T cells and examined for evidence of transition to a mesenchymal phenotype. Liver sections were labelled to detect antigens associated with biliary epithelial cells (cytokeratin 7 and 19 and E-cadherin), T cells (CD8), epithelial-mesenchymal transition (S100A4, vimentin and matrix metalloproteinase-2 (MMP-2)), myofibroblasts (alpha-smooth muscle actin) and intracellular signal-transduction mediated by phosphorylated (p)Smad 2/3; in situ hybridisation was performed to detect mRNA encoding TGFbeta and S100A4. Stimulation of cultured cells with TGFbeta induced the expression of pSmad2/3, S100A4 and alpha-smooth muscle actin; these cells became highly motile. Although normal bile ducts expressed ALK5 (TGFbeta RI), low levels of TGFbeta mRNA and nuclear pSmad2/3, they did not express S100A4, vimentin or MMP-2. However, TGFbeta mRNA and nuclear pSmad2/3 were strongly expressed in damaged ducts, which also expressed S100A4, vimentin and MMP-2. Fibroblast-like cells which expressed S100A4 were present around many damaged bile ducts. Cells in the 'ductular reaction' expressed both epithelial and mesenchymal markers together with high levels of TGFbeta mRNA and pSmad2/3. In conclusion, the cells forming small- and medium-sized bile ducts and the ductular reaction undergo EMT during chronic liver diseases, resulting in the formation of invasive fibroblasts; this process may be driven by a response to local TGFbeta, possibly presented by infiltrating T cells.

The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.