39 research outputs found
Effect of Ceramic Scaffold Architectural Parameters on Biological Response.
Numerous studies have focused on the optimization of ceramic architectures to fulfill a variety of scaffold functional requirements and improve biological response. Conventional fabrication techniques, however, do not allow for the production of geometrically controlled, reproducible structures and often fail to allow the independent variation of individual geometric parameters. Current developments in additive manufacturing technologies suggest that 3D printing will allow a more controlled and systematic exploration of scaffold architectures. This more direct translation of design into structure requires a pipeline for design-driven optimization. A theoretical framework for systematic design and evaluation of architectural parameters on biological response is presented. Four levels of architecture are considered, namely (1) surface topography, (2) pore size and geometry, (3) porous networks, and (4) macroscopic pore arrangement, including the potential for spatially varied architectures. Studies exploring the effect of various parameters within these levels are reviewed. This framework will hopefully allow uncovering of new relationships between architecture and biological response in a more systematic way as well as inform future refinement of fabrication techniques to fulfill architectural necessities with a consideration of biological implications.The authors gratefully acknowledge the financial support of the Gates Cambridge Trust and Geistlich Pharma AG.This is the final version of the article. It first appeared from Frontiers via http://dx.doi.org/10.3389/fbioe.2015.0015
How does the radio enhancement of broad absorption line quasars relate to colour and accretion rate?
The origin of radio emission in different populations of radio-quiet quasars is relatively unknown, but recent work has uncovered various drivers of increased radio-detection fraction. In this work, we pull together three known factors: optical colour (g - i), C IV distance (a proxy for L/LEdd), and whether or not the quasar contains broad absorption lines (BALQSOs) which signify an outflow. We use SDSS (Sloan Digital Sky Survey) DR14 spectra along with the LOFAR Two Metre Sky Survey Data Release 2 and find that each of these properties have an independent effect. BALQSOs are marginally more likely to be radio-detected than non-BALQSOs at similar colours and L/LEdd, moderate reddening significantly increases the radio-detection fraction and the radio detection increases with L/LEdd above a threshold for all populations. We test a widely used simple model for radio wind shock emission and calculate energetic efficiencies that would be required to reproduce the observed radio properties. We discuss interpretations of these results concerning radio-quiet quasars more generally. We suggest that radio emission in BALQSOs is connected to a different physical origin than the general quasar population since they show different radio properties independent of colour and C IV distance
LOFAR/H-ATLAS: The low-frequency radio luminosity - star-formation rate relation
Radio emission is a key indicator of star-formation activity in galaxies, but
the radio luminosity-star formation relation has to date been studied almost
exclusively at frequencies of 1.4 GHz or above. At lower radio frequencies the
effects of thermal radio emission are greatly reduced, and so we would expect
the radio emission observed to be completely dominated by synchrotron radiation
from supernova-generated cosmic rays. As part of the LOFAR Surveys Key Science
project, the Herschel-ATLAS NGP field has been surveyed with LOFAR at an
effective frequency of 150 MHz. We select a sample from the MPA-JHU catalogue
of SDSS galaxies in this area: the combination of Herschel, optical and
mid-infrared data enable us to derive star-formation rates (SFRs) for our
sources using spectral energy distribution fitting, allowing a detailed study
of the low-frequency radio luminosity--star-formation relation in the nearby
Universe. For those objects selected as star-forming galaxies (SFGs) using
optical emission line diagnostics, we find a tight relationship between the 150
MHz radio luminosity () and SFR. Interestingly, we find that a single
power-law relationship between and SFR is not a good description of
all SFGs: a broken power law model provides a better fit. This may indicate an
additional mechanism for the generation of radio-emitting cosmic rays. Also, at
given SFR, the radio luminosity depends on the stellar mass of the galaxy.
Objects which were not classified as SFGs have higher 150-MHz radio luminosity
than would be expected given their SFR, implying an important role for
low-level active galactic nucleus activity.Comment: 21 pages, 12 figures, accepted for publication in MNRA
The LOFAR Two-metre Sky Survey: The nature of the faint source population and SFR–radio luminosity relation using prospector
VizieR Online Data Catalog: Bootes field deep LOFAR 150MHz imaging (Retana-Montenegro+, 2018)
The LOFAR mosaic image of the Bootes field and its corresponding source catalog are presented here. The mosaic image is obtained using 55 hours of observations, and it has a central rms noise of 0.255mJy/beam and an angular resolution of 3.98"x6.45"
Epidemiology of emergency ambulance service calls related to mental health problems and self harm: a national record linkage study.
Background: People experiencing a mental health crisis receive variable and poorer quality care than those experiencing a physical health crisis. Little is known about the epidemiology, subsequent care pathways of mental health and self-harm emergencies attended by ambulance services, and subsequent all-cause mortality, including deaths by suicide. This is the first national epidemiological analysis of the processes and outcomes of people attended by an ambulance due to a mental health or self-harm emergency. The study aimed todescribe patient characteristics, volume, case-mix, outcomes and care pathways following ambulance attendance in this patient population.Methods: A linked data study of Scottish ambulance service, emergency department, acute inpatient and death records for adults aged ?16 for one full year following index ambulance attendance in 2011.Results: The ambulance service attended 6802 mental health or self harm coded patients on 9014 occasions. This represents 11% of all calls attended that year. Various pathways resulted from these attendances. Most frequent were those that resulted in transportation to and discharge from the emergency department (n =4566/9014; 51%). Some patients were left at home (n = 1003/9014 attendances, 11%). Others were admitted to hospital (n = 2043/9014, 23%). Within 12 months of initial attendance, 279 (4%) patients had died, 97 of these were recorded as suicide.Conclusions: This unique study finds that ambulance service and emergency departments are missing opportunities to provide better care to this population and in potentially avoidable mortality, morbidity and service burden. Developing and testing interventions for this patient group in pre-hospital and emergency department settings could lead to reductions in suicide, patient distress, and service usag
VizieR Online Data Catalog: LOFAR observations XMM-LSS field (Hale+, 2019)
Catalogues of the LOFAR sources observed in the XMM-LSS Field. (4 data files)
VizieR Online Data Catalog: Broad absorption line quasars in LDR1 (Morabito+, 2019)
Measured and derived parameters for quasars from the SDSS DR7/DR12 catalogs within the footprint of the LOFAR Two-metre Sky Survey data realease 1 (LDR1). This is a combination of data from SDSS DR7/DR12, with accretion properties from Shen et al., (2011, Cat. J/ApJS/194/45) and Kozlowski (2017. Cat. J/ApJS/228/9). Radio properties from LDR1 and FIRST are presented. (1 data file)
Cosmic evolution of low-excitation radio galaxies in the LOFAR two-meter sky survey deep fields
Abstract Feedback from low-excitation radio galaxies (LERGs) plays a key role in the lifecycle of massive galaxies in the local Universe; their evolution, and the impact of these active galactic nuclei on early galaxy evolution, however, remain poorly understood. We use a sample of 10 481 LERGs from the first data release of the LOFAR Two-meter Sky Survey Deep Fields, covering ∼ 25 deg2, to present the first measurement of the evolution of the radio luminosity function (LF) of LERGs out to z ∼ 2.5; this shows relatively mild evolution. We split the LERGs into those hosted by quiescent and star-forming galaxies, finding a new dominant population of LERGs hosted by star-forming galaxies at high redshifts. The incidence of LERGs in quiescent galaxies shows a steep dependence on stellar-mass out to z ∼ 1.5, consistent with local Universe measurements of accretion occurring from cooling of hot gas haloes. The quiescent-LERGs dominate the LFs at z < 1, showing a strong decline in space density with redshift, tracing that of the available host galaxies, while there is an increase in the characteristic luminosity. The star-forming LERG LF increases with redshift, such that this population dominates the space densities at most radio-luminosities by z ∼ 1. The incidence of LERGs in star-forming galaxies shows a much weaker stellar-mass dependence, and increases with redshift, suggesting a different fuelling mechanism compared to their quiescent counterparts, potentially associated with the cold gas supply present in the star-forming galaxies
Relocation to get venture capital : a resource dependence perspective
This is the author accepted manuscript. The final version is available from SAGE via the DOI in this record.Using a resource dependence perspective, we theorize and show that non-venture-capital-backed ventures founded in U.S. states with a lower availability of venture capital (VC) are more likely to relocate to California (CA) or Massachusetts (MA)—the two VC richest states—compared to ventures founded in states with a greater availability of VC. Moreover, controlling for self-selection, ventures that relocate to CA or MA subsequently have a greater probability of attracting initial VC compared to ventures that stay in their home state. We discuss the implications for theory, future research, and practice