50 research outputs found
The Dual-Rasp Sampling System for an Enceladus Lander
The Dual-Rasp sampling system has been developed for the unique sampling environment of a lander mission to the surface of Saturn's moon Enceladus. Plume material from the subsurface ocean that has fallen to the surface is desired resulting in an objective to sample the topmost layer of icy material. The low gravity and potential large range of surface properties are challenges for the sampling system. The Dual-Rasp sampling system has two counter-rotating rasp cutters with teeth that remove material that is thrown up between the cutters. Two prototypes of the Dual-Rasp sampling system were built and tested, one with a carousel and one that uses pneumatics for sample transfer
What is the role of public feeder markets in developing technology-based small firms? An exploration of the motivations for listing on AIM since the GFC
In the aftermath of the 2007 global financial crisis (GFC) stock markets experienced sharp decline in listings and marked reduction in Initial Public Offerings (IPOs). This paper explores the factors determining UK technology based small firm (TBSF) listings on the UK Alternative Investment Market (AIM) and whether this market has a role to play in their future development.
A case study approach is used to contrast the experiences of five recent AIM listed TBSFs with five TBSFs approaching private equity investment exit that are considering an IPO.
The paper concludes that macro market conditions, rather than managerial resource base or AIM market structural factors were most influential in TBSF pecking order preferences to undertake IPOs. From a resource based management perspective lifelong entrepreneurs were more likely than serial entrepreneurs to favour an IPO exit, as it supported their aims to continue to manage and grow UK-based companies. Additionally, with a more buoyant and sustainable AIM market TBSF investors are more likely to choose IPOs. To conclude, AIM played an important role in listed UK TBSF development. A more buoyant AIM could ease the UK finance escalatorâs flow, facilitating more rapid UK TBSF growth
Dynamical simulation of DCC formation in Bjorken rods
Using a semi-classical treatment of the linear sigma model, we simulate the
dynamical evolution of an initially hot cylindrical rod endowed with a
longitudinal Bjorken scaling expansion (a ``Bjorken rod''). The field equation
is propagated until full decoupling has occurred and the asymptotic many-body
state of free pions is then obtained by a suitable Fourier decomposition of the
field and a subsequent stochastic determination of the number of quanta in each
elementary mode. The resulting transverse pion spectrum exhibits visible
enhancements below 200 MeV due to the parametric amplification caused by the
oscillatory relaxation of the chiral order parameter. Ensembles of such final
states are subjected to various event-by-event analyses. The factorial moments
of the multiplicity distribution suggest that the soft pions are
non-statistical. Furthermore, their emission patterns exhibit azimuthal
correlations that have a bearing on the domain size in the source. Finally, the
distribution of the neutral pion fraction shows a significant broadening for
the soft pions which grows steadily as the number of azimuthal segments is
increased. All of these features are indicative of disoriented chiral
condensates and it may be interesting to apply similar analyses to actual data
from high-energy nuclear collision experiments.Comment: 38 pages total, incl 26 ps figures ([email protected]
Host Galaxy Properties and Offset Distributions of Fast Radio Bursts: Implications for Their Progenitors
We present observations and detailed characterizations of five new host galaxies of fast radio bursts (FRBs) discovered with the Australian Square Kilometre Array Pathfinder (ASKAP) and localized to ⟠1". Combining these galaxies with FRB hosts from the literature, we introduce criteria based on the probability of chance coincidence to define a subsample of 10 highly confident associations (at z = 0.03â0.52), 3 of which correspond to known repeating FRBs. Overall, the FRB-host galaxies exhibit a broad, continuous range of color (M_u â M_r = 0.9â2.0), stellar mass (M_â
= 10âž â 6 Ă 10Âčâ° M_â), and star formation rate (SFR = 0.05â10 M_â yrâ»Âč) spanning the full parameter space occupied by z 99% c.l.). We measure a median offset of 3.3 kpc from the FRB to the estimated center of the host galaxies and compare the host-burst offset distribution and other properties with the distributions of long- and short-duration gamma-ray bursts (LGRBs and SGRBs), core-collapse supernovae (CC-SNe), and SNe Ia. This analysis rules out galaxies hosting LGRBs (faint, star-forming galaxies) as common hosts for FRBs (>95% c.l.). Other transient channels (SGRBs, CC-, and SNe Ia) have host-galaxy properties and offsets consistent with the FRB distributions. All of the data and derived quantities are made publicly available on a dedicated website and repository
One and two dimensional analysis of 3pi correlations measured in Pb+Pb interactions
3pi- correlations from Pb+Pb collisions at 158 GeV/c per nucleon are
presented as measured by the focusing spectrometer of the NA44 experiment at
CERN. The three-body effect is found to be stronger for PbPb than for SPb. The
two-dimensional three-particle correlation function is also measured and the
longitudinal extension of the source is larger than the transverse extension
Removal of a bent tibial intramedullary nail: a rare case
ăAbstractăIntramedullary interlocking nailing is a
gold standard for treatment of tibial shaft fractures. Bending
of a nail secondary to trauma is a rare complication,
which may be encountered in healed or unhealed tibial shaft
fractures. Removal of such bent nail is always a challenge.
We reported this case to discuss various techniques for
removal of bent nails and to share our experience in removing
a bent tibial intramedullary nail in a 30-year-old man,
who was admitted in our department with re-fracture of the
right tibial shaft due to a roadside accident two years after
the initial surgical treatment. The intramedullary nail, bent by
30 degrees and visible on anterioposterior as well as on lateral
radiographs, was firstly weakened by partially cutting
the convex wall, then straightened by applying external force,
and finally removed by using the standard nail removal
method.
Key words: Fracture fixation, intramedullary; Tibial
fractures; Device remova
Endovascular training using a simulation-based curriculum is less expensive than training in the hybrid angiosuite
Background and aims: Traditionally, endovascular procedures are trained on real patients, without structured curricular support and dependent on a highly variable caseload. This study aimed to determine the cost-effectiveness of a PROficiency-based StePwise Endovascular Curricular Training (PROSPECT) program including e-learning and hands-on virtual-reality simulation.
Methods: A prospective single-blinded Randomized Controlled Trial (RCT) evaluated endovascular performance of surgical trainees after conventional training (N=11), conventional training and e-learning (N=10) or structured training using the PROSPECT program (N=11). Subjects performed two supervised endovascular interventions (symptomatic iliac and/or superficial femoral artery stenosis). An analysis was performed of costs and savings related to implementation of the PROSPECT program. Developmental cost, implementation cost, training time cost and operational costs were determined. Time spent studying and practicing was converted into indirect saving of operating time. Costs of logistics, faculty time supervising simulation sessions and 30-day complication rates were registered. Sensitivity analysis was performed
Results: Fifty-eight peripheral endovascular interventions, performed by 29 surgical trainees (3 drop-outs) were included in this RCT from October 2014 to February 2016. Yearly costs for the hospital include 6,589⏠for curriculum design, 31,484⏠for implementation and 1,143⏠operational costs. Per trainee at our university, simulation-based training until proficiency would require 3,806⏠in total, while obtaining endovascular proficiency levels during conventional training only, may have costed 5,001⏠per trainee.
Conclusions: Simulation-based training in endovascular procedures may be cost saving, because training occurs outside the angiosuite. Cost savings are possibly underestimated since prevented costs related to complications could not be defined