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Background: Spinal muscular atrophy (SMA) is a children’s neuromuscular disorder. Although motor neuron loss is a major feature of the disease, we have identified fatty acid abnormalities in SMA patients and in preclinical animal models, suggesting metabolic perturbation is also an important component of SMA. Methods: Biochemical, histological, proteomic, and high resolution respirometry were used. Results: SMA patients are more susceptible to dyslipidemia than the average population as determined by a standard lipid profile in a cohort of 72 pediatric patients. As well, we observed a non-alcoholic liver disease phenotype in apreclinical mouse model. Denervation alone was not sufficient to induce liver steatosis, as a mouse model of ALS, did not develop fatty liver. Hyperglucagonemia in Smn2B/-mice could explain the hepatic steatosis by increasing plasma substrate availability via glycogen depletion and peripheral lipolysis. Proteomic analysis identified mitochondrion and lipid metabolism as major clusters. Alterations in mitochondrial function were revealed by high-resolution respirometry. Finally, low-fat diets led to increased survival in Smn2B/-mice. Conclusions: These results provide strong evidence for lipid metabolism defects in SMA. Further investigation will be required to establish the primary mechanism of these alterations and understand how they lead to additional co-morbidities in SMA patients.
The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.
We discuss GHRS spectra of single and binary late-type stars and describe in detail the spectra of α TrA and of ζ Aurigae obtained at ten orbital phases. The wind properties of α TrA are derived using a complete redistribution radiative transfer code, and we describe the properties of a new code, PRISMA, that we are building to fit line profiles using partial redistribution in a spherically-symmetric geometry. The ζ Aur spectra show that the mass loss process is variable on the timescale of several months, the wind density structure does not repeat from orbit to orbit, and the wind ionization structure is complex.
During the past three years the measurement of stellar radial velocities has formed an important part of the spectroscopic programme of most observatories possessing large telescopes. As observations are carried to fainter and fainter stars and the number of observable objects increases rapidly, a natural development has been the selection of special groups and types of stars, the radial velocities of which will aid in the solution of certain specific problems. Illustrations are the studies of the O, B and A type stars made at the Dominion Astrophysical, the Lick, and the Simeis Observatories, of the members of the galactic clusters at the Lick Observatory, and of the fainter Cepheid variables and early-type stars with strong interstellar lines at the Mount Wilson Observatory.
Multi-wavelength studies of M supergiants have revealed atmospheric structures with a
large range of spatial and temporal scales. Focusing on Betelgeuse, these scales and their
perplexing connections from the photosphere to the interstellar medium are reviewed. Of
particular current interest is the dynamic origin of the ubiquitous and relatively
dust-free mass loss. Is it multiple plumes of convection driven ejecta, episodic ejection
of molecular reservoirs, or a more steady and uniform flow? With powerful new facilities
such as the VLT and ALMA we may begin to understand the connections and answer such
puzzles, but ultimately detailed studies of a sample of M supergiants will be needed to
disentangle the physics from the stars’ personalities.
Treatment options for large subglottic haemangioma include steroids, laser ablation, open excision, tracheostomy and, more recently, propranolol. This article aims to present the Great Ormond Street Hospital guidelines for using propranolol to treat infantile isolated subglottic haemangioma by ENT surgeons.
The vascular malformations multidisciplinary team at Great Ormond Street Hospital has developed guidelines for treating infantile haemangioma with propranolol.
The Great Ormond Street Hospital guidelines for propranolol treatment for infantile subglottic haemangioma include investigation, treatment and follow up. Propranolol is started at 1 mg/kg/day divided into three doses, increasing to 2 mg/kg/day one week later. On starting propranolol and when increasing the dose, the pulse rate and blood pressure must be checked every 30 minutes for the first 2 hours. Lesion response to treatment is assessed via serial endoscopy.
Recent reports of dramatic responses to oral propranolol in children with haemangioma and acute airway obstruction have led to increased use. We advocate caution, and have developed guidelines (including pre-treatment investigation and monitoring) to improve treatment safety. Propranolol may in time prove to be the best medical treatment for subglottic haemangioma, but at present is considered to be still under evaluation.
Polarimetry at far-infrared wavelengths is a key tool for studying physical processes on size scales ranging from interstellar dust grains to entire galaxies. A multi-wavelength continuum polarimeter at these wavelengths will allow studies of thermal dust polarization in an effort to constrain the grains’ physical properties and test grain alignment theory. High spatial resolution (5–30 arcsec) and sensitive observations will measure the influence of magnetic fields on infrared cirrus clouds, the envelopes and disks of YSOs, outflows from both low- and high-mass star forming regions, and the relative strength of magnetic, gravitational, and turbulent effects in star- and cloud-formation.
Thermal wave imaging can be used as a rapid non-destructive in-line probe to monitor defects in metals. In the study of the Ti-polysilicon system, this technique has been used to quantify the degradation of the suicide film by monitoring the formation of a second phase during BPSG annealing. The amount of second phase formed was found to vary with Ti preclean, dopant concentration and temperature of BPSG anneal on both blanket and patterned wafers. The second phase has been identified using TEM and AES to be a silicon rich phase. Digitized thermal wave images were used to obtain information regarding the size distribution of precipitates. These distributions have been correlated with resistivity changes in submicron suicide lines.
The formation of NiSi and NiSi2 upon annealing of an ion-amorphized Ni/Si structure has been studied by various surface analytical techniques to characterize the morphology, stoichiometry and interface sharpness of the NiSi2 layer. In comparison with reactions of nickel on crystalline silicon (c-Si), sharpening 0ofthe NiSi2/C-Si interface is obtained for appropriate amorphization depths. Moreover, the surface roughness of the NiSi2 films is significantly reduced by implantation. The NiSi2 formation temperature is, however, not reduced as observed for structures with nickel deposited on amorphous silicon prepared by evaporation. This dissimilarity can be explained by an unexpected low crystallization temperature or the ion-amorphized structure, where Ni-ennanced solid phase epitaxy occurs at a temperature as low as 425°C.
IBS of buried α and β iron suicide layers was achieved by the implantation of 2 MeV 56Fe+ ions into (100) single crystal silicon substrates over a dose range of 3 × 1017 to 1 × 1018 cm“-2followed by a high temperature anneal. No photoluminescence was observed from the as-implanted samples which contained a discontinuous layer of βFeSi2 precipitates approximately 1.5 μm below the silicon surface. Upon annealing at 700°C, a 200 nm polycrystalline βFeSi2 layer was formed which gave a PL signal centred at 1.55 μm. After a 900°C anneal, the layer transformed to αFeSix with a resistivity of approximately 280μΩcm.
The thermally-induced Co/SixGe1-x reaction has been studied for a series of isochronal (25–600°C/20 min) and isothermal (600°C/u-240 min) annealing sequences using Rutherford backscattering spectrometry, transmission electron microscopy and sheet resistance measurements. Annealing at 600°C yields a reacted surface layer comprised of Si-rich CoSixGe1-x, Ge-rich SiyGe1-y and possibly CoSi2, with the two former constituents exhibiting a degree of epitaxial alignment with the substrate. The formation of Co/SiSixGe1-x alloys is discussed in terms of the ternary phase diagram.
The current/voltage characteristics of ion beam synthesised CoSi2/Si (n - type) Schottky barrier diodes implanted with phosphorus to doses between 5 × 1012 and 2 × 1013 ions cm-2are examined after annealing at temperatures in the range 400° - 1000°C. For each dose of implanted phosphorus, the effective barrier height of the CoSi2/Si interface is successively reduced as the anneal temperature increases. The results of Secondary Ion Mass Spectroscopy (SIMS) analysis indicate that these changes are due to an increase in the space charge density at the interface. For lower annealing temperatures the increase in space charge density is attributed to activation of the phosphorus in the tail of the dopant distribution which extends across the CoSi2/Si interface. For higher annealing temperatures larger increases in the space charge density are attributed to a modified dopant distribution resulting from phosphorus diffusion and activation at the interface. For doses of 1 × 1014 P* cm-2and 2×1015P*cm2, ohrnie characteristics are seen after annealing at temperatures of 1000°C and 500°C respectively.
Chemical Vapour Deposition of tungsten on silicon dioxide by means of GeH4 reduction of WF6 is studied. The influence of the ambient gas on the nucleation of tungsten is examined. Experiments have been performed in both Ar and H2 ambient. It is found that an Ar ambient hinders nucleation on silicon dioxide in comparison with a hydrogen ambient. Adhesion of the film and uniformity over the wafer are acceptable for the films deposited in hydrogen ambient.
The electrical and interface parameters of epitaxial orthorombic, textured orthorombic, polycrystalline orthorombic, and polycrystalline hexagonal structures with different initial thickness of the evaporated Gd layer are compared. The Schottky barrier height, the ideality factor, the series resistance, the breakdown voltage, the relative interfacial layer thickness, the energy distribution spectra of interface states, and the equilibrium interface charge have been evaluated from the current-voltage and capacitance-voltage measurements. The obtained results indicate that the initial thickness of the Gd layer influences much more stronger the obtained parameters through the perfection of the epitaxial layer than the crystal structure.
Redistribution of boron during the formation of the cobalt suicides Co2Si, CoSi and CoSi2 has been studied. The suicides were formed by solid state reactions of cobalt deposited on boron implanted silicon. The suicide formation was determined by Rutherford backseat tering spectrometry (RBS), and the resulting redistribution of boron was studied using secondary ion mass spectrometry (SIMS). The study shows that the atoms participating in the suicide formation diffuse in the growing suicide without any mutual interference. Boron atoms in the consumed silicon layer redistribute within the formed suicide layer and accumulate at the surface, while boron in the underlying unconsumed silicon is unaltered, and no accumulation due to snowplowing occurs at the silicide/silicon interface.
Picosecond ultrasonics is employed to study the titanium silicide formation sequence for evaporated Ti films on silicon substrates annealed at temperatures between 300 and 800 °C. The measurements show significant differences in the ultrasonic echo pattern before and after the structural phases C49 and C54 are formed, thus indicating that picosecond ultrasonics is a sensitive non-destructive probe of silicide formation. The longitudinal sound velocity has been found to be (8.3 ± 0.2) × 105 cm/sec for C49 TiSi2, and about 5% lower for the C54 phase.