Abstract
A significant number of active galactic nuclei (AGNs) are observed to be hidden behind dust and gas. The distribution of material around AGNs plays an important role in modelling the cosmic ...X-ray background (CXB), especially the fraction of type 2 AGNs (f2). One of the possible explanations for obscuration in Seyfert galaxies at intermediate redshifts is dusty starburst discs. We compute the two-dimensional (2D) hydrostatic structure of 768 nuclear starburst discs (NSDs) under various physical conditions and also the distribution of column density along the line of sight (NH) associated with these discs. Then the NH distribution is evolved with redshift by using the redshift-dependent distribution function of input parameters. Parameter f2 shows a strong positive evolution up to z = 2, but only a weak level of enhancement at higher z. The Compton-thin and Compton-thick AGN fractions associated with these starburst regions increase ∝ (1 + z)δ, where δ is estimated to be 1.12 and 1.45, respectively. The reflection parameter Rf associated with column density NH ≥ 1023.5 cm−2 extends from 0.13 at z = 0 to 0.58 at z = 4. A CXB model employing this evolving NH distribution indicates that more compact (Rout < 120 pc) NSDs provide a better fit to the CXB. In addition to ‘Seyfert-like’ AGNs obscured by nuclear starbursts, we predict that 40–60 per cent of quasars must be Compton-thick to produce a peak of the CXB spectrum within the observational uncertainty. The predicted total number counts of AGNs in 8–24 keV bands are in fair agreement with observations from the Nuclear Spectroscopic Telescope Array (NuSTAR).
This paper aims to review the state of the art of Light Detection and Ranging (LiDAR) sensors for automotive applications, and particularly for automated vehicles, focusing on recent advances in the ...field of integrated LiDAR, and one of its key components: the Optical Phased Array (OPA). LiDAR is still a sensor that divides the automotive community, with several automotive companies investing in it, and some companies stating that LiDAR is a 'useless appendix'. However, currently there is not a single sensor technology able to robustly and completely support automated navigation. Therefore, LiDAR, with its capability to map in 3 dimensions (3D) the vehicle surroundings, is a strong candidate to support Automated Vehicles (AVs). This manuscript highlights current AV sensor challenges, and it analyses the strengths and weaknesses of the perception sensor currently deployed. Then, the manuscript discusses the main LiDAR technologies emerging in automotive, and focuses on integrated LiDAR, challenges associated with light beam steering on a chip, the use of Optical Phased Arrays, finally discussing current factors hindering the affirmation of silicon photonics OPAs and their future research directions.
To review the literature on epidemiology, clinical features, diagnostic imaging, natural history, management, therapeutic approaches, and prognosis of myopic foveoschisis. A systematic Pubmed search ...was conducted using search terms: myopia, myopic, staphyloma, foveoschisis, and myopic foveoschisis. The evidence base for each section was organised and reviewed. Where possible an authors' interpretation or conclusion is provided for each section. The term myopic foveoschisis was first coined in 1999. It is associated with posterior staphyloma in high myopia, and is often asymptomatic initially but progresses slowly, leading to loss of central vision from foveal detachment or macular hole formation. Optical coherence tomography is used to diagnose the splitting of the neural retina into a thicker inner layer and a thinner outer layer, but compound variants of the splits have been identified. Vitrectomy with an internal limiting membrane peel and gas tamponade is the preferred approach for eyes with vision decline. There has been a surge of new information on myopic foveoschisis. Advances in optical coherence tomography will continually improve our understanding of the pathogenesis of retinal splitting, and the mechanisms that lead to macular damage and visual loss. Currently, there is a good level of consensus that surgical intervention should be considered when there is progressive visual decline from myopic foveoschisis.
ABSTRACT
Nuclear starburst discs (NSDs) are very compact star-forming regions in the centres of galaxies that have been studied as a possible origin for the absorbing gas around a central active ...galactic nucleus. NSDs may be most relevant at $z$ ∼ 1 when obscured accretion on to supermassive black holes (SMBHs) is common. This paper describes the characteristics of the stellar remnants of NSDs at $z$ = 0.01, taking into account the evolution from $z$ = 1. Using a stellar synthesis model, the colours, masses, and luminosities of the stellar remnants are computed for a suite of 192 two-dimensional NSD models. These properties are compared to observations of local nuclear star clusters (NSCs), and a good match is found between the predicted and observed properties. Dynamical effects will likely cause the final remnant to be a rotating, nearly spherical distribution. In addition, ≈20 per cent of the NSD remnants have half-light radii $\lesssim \! 10$ pc, consistent with NSCs hosted in both late- and early-type galaxies, and all the remnants follow similar size–luminosity relationships as observed in nearby NSCs. NSDs require the presence of a central SMBH and the most massive and compact stellar remnants are associated with the most massive SMBHs, although stellar clusters with a variety of sizes can be produced by all considered SMBH masses. Overall, NSDs at $z$ ∼ 1 appear to be a promising origin for the ≫1 Gyr NSC population in early- and late-type galaxies with large SMBHs.
Powered wheelchairs and motorised mobility scooters, collectively called powered mobility devices (PMD), are highly valued by older Australians, including those living in residential care, to ...facilitate personal and community mobility. The number of PMDs in residential aged care is expected to grow proportionally with that of the wider community, however, there is very little literature on supporting residents to use PMDs safely. Prior to developing such supports, it is important to understand the frequency and nature of any incidents experienced by residents whilst using a PMD. The aim of this study was to determine the number and characteristics of PMD use related incidents occurring in a group of residential aged care facilities in a single year in one state in Australia including incident type, severity, assessment, or training received and outcomes on follow-up for PMD users living in residential aged care.
Analysis of secondary data, including documentation of PMD incidents and injuries for one aged care provider group over 12 months retrospectively. Follow-up data were gathered 9-12 months post incident to review and record the outcome for each PMD user.
No fatalities were recorded as a direct result of PMD use and 55 incidents, including collisions, tips, and falls, were attributed to 30 residents. Examination of demographics and incident characteristics found that 67% of residents who had incurred incidents were male, 67% were over 80 years of age, 97% had multiple diagnoses and 53% had not received training to use a PMD. Results from this study were extrapolated to project that 4,453 PMD use related incidents occur every year within Australian residential aged care facilities, with the potential for outcomes such as extended recovery, fatality, litigation, or loss of income.
This is the first time that detailed incident data on PMD use in residential aged care has been reviewed in an Australian context. Illuminating both the benefits and the potential risks of PMD use emphasizes the need to develop and improve support structures to promote safe PMD use in residential aged care.
Background
Historically dacryocystorhinostomy (DCR) has been performed externally with very good outcomes. Current literature shows comparable success rates between endonasal and external approaches. ...A common reason for the failure of a DCR is the reclosure of the nasolacrimal stoma by granulation tissue and synechiae.
Objective of review
A systematic review and critical evaluation of the evidence relating to the preservation of nasal mucosal flaps in DCR surgery.
Type of review and evaluation method
A systematic review using the consort guidance for review of randomised control trials.
Search strategy
A search of the following evidence‐based medicine databases was performed: Cochrane Database of Systematic Reviews, Database of s of Reviews of Effectiveness, Cochrane Central Register of Controlled Trials, Ovid, Medline, EMBASE and PubMed. The search was limited to English language articles, and the following key words were used: Endonasal, Endoscopic, Dacryocystorhinostomy, DCR, Mucosal Flaps, between years 1970 and 2015.
Results
The best available evidence was level 1B, comprising two randomised control trials and three comparative studies included in the review. The main outcome measures used were lacrimal irrigation and absence of epiphora. Two of the studies demonstrated a statistically significant benefit of mucosal sparing either with nasal mucosal flaps or with lacrimal flaps. More debridement was needed, and granulation tissue was also seen in the groups without mucosal preservation. There was no difference in surgical complications between a mucosal and non‐mucosal‐sparing technique.
Conclusions
The overall quality of current evidence is poor, and there does however appear to be a trend towards improved outcomes and reduced granulation in groups where nasal mucosal and lacrimal flaps were preserved, but this is not clear‐cut. There was no evidence of increased complication rates with mucosal‐sparing techniques. We recommend that until further good quality research is available we should be performing a mucosal‐sparing technique when performing DCR routinely.
Obscured active galactic nuclei (AGNs) provide an opportunity to study the material surrounding the central engine. Geometric and physical constraints on the absorber can be deduced from the ...reprocessed AGN emission. In particular, the obscuring gas may reprocess the nuclear X-ray emission producing a narrow Fe Kα line and a Compton reflection hump. In recent years, models of the X-ray reflection from an obscuring torus have been computed; however, although the reflecting gas may be dusty, the models do not yet take into account the effects of dust on the predicted spectrum. We study this problem by analysing two sets of models, with and without the presence of dust, using the one-dimensional photoionization code cloudy. The calculations are performed for a range of column densities (22 < logN
H(cm− 2) < 24.5) and hydrogen densities (6 < logn
H(cm− 3) < 8). The calculations show the presence of dust can enhance the Fe Kα equivalent width (EW) in the reflected spectrum by factors up to ≈8 for Compton thick (CT) gas and a typical interstellar medium grain size distribution. The enhancement in EW with respect to the reflection continuum is due to the reduction in the reflected continuum intensity caused by the anisotropic scattering behaviour of dust grains. This effect will be most relevant for reflection from distant, predominately neutral gas, and is a possible explanation for AGNs which show a strong Fe Kα EW and a relatively weak reflection continuum. Our results show it is an important to take into account dust while modelling the X-ray reflection spectrum, and that inferring a CT column density from an observed Fe Kα EW may not always be valid. Multidimensional models are needed to fully explore the magnitude of the effect.
Allium sativum germplasm collected from different parts of India was subjected to critical analysis of 14 easily noticeable morphological traits. Variability encountered in quantitative as well as ...qualitative, bulb and plant traits was documented. While analysing this variability, an attempt was made to highlight the genotype-environment interaction, its impact on the expression of morphological traits in this apomict and evaluate the different collections for intraspecific phylogeny.
Adult laryngeal haemangiomas are rare vascular tumours that have been managed by a variety of surgical techniques.
This paper describes a case of near-fatal acute airway obstruction secondary to such ...a lesion, followed by our approach to surgical resection using a laparoscopic bipolar tissue-sealing device.
This technique resulted in successful excision of the lesion, with no evidence of recurrence at one year of follow up.
Laparoscopic bipolar instruments can be used for the resection of moderate to large laryngeal haemangiomas as an alternative to laser excision.
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