1,516 research outputs found
Radiation Damage of F8 Lead Glass with 20 MeV Electrons
Using a 20 MeV linear accelerator, we investigate the effects of
electromagnetic radiation on the optical transparency of F8 lead glass.
Specifically, we measure the change in attenuation length as a function of
radiation dose. Comparing our results to similar work that utilized a proton
beam, we conclude that F8 lead glass is more susceptible to proton damage than
electron damage.Comment: 5 pages, 6 figure
Safety training for migrant workers in the construction industry: A systematic review and future research agenda
In the construction sector, there is a high risk for accidents, injuries, and fatalities, particularly for migrant workers who comprise a large proportion of the workforce. This article presents a systematic literature review of current safety training provision for migrant construction workers. In the interests of rigor, we draw on the learning, training transfer, and training effectiveness literatures, exploring not only the extent to which training brings about the intended outcomes, in terms of enhanced safety behaviors, and reduced accidents and injuries, but also the factors that influence learning and transfer of training back to the working environment. The literature search revealed only 18 peer-reviewed articles have been published since 2000, which is particularly surprising, given the disproportionate accident and fatality rates for migrant workers. Consequently, we propose a research agenda to enhance safety training for low skilled, migrant and native construction workers, drawing on cognitive and social constructivist instructional design models, which view training as a dynamic process involving active participation of trainees. We advocate the importance of attending to the situational context in which workers are embedded, including labor market conditions, social relations, and cultural differences. Finally, we propose the need for further longitudinal, multidimensional research to evaluate the impact of safety training on learning, transfer of training, and individual- and organizational-level outcomes, such as behavior change, and accident and fatality rates
Continuous-wave and passively Q -switched cladding-pumped planar waveguide lasers
Greater than 12W of average output power has been generated from a diode-pumped YbYAG cladding-pumped planar waveguide laser. The laser radiation developed is linearly polarized and diffraction limited in the guiding dimension. A slope efficiency of 0.5WW with a peak optical optical conversion efficiency of 0.31WW is achieved. In a related structure, greater than 8W of Q -switched average output power has been generated from a NdYAG cladding-pumped planar waveguide laser by incorporation of a Cr 4+ YAG passive Q switch monolithically into the waveguide structure. Pulse widths of 3ns and pulse-repetition frequencies as high as 80kHz have been demonstrated. A slope efficiency of 0.28WW with a peak optical optical conversion efficiency of 0.21WW is achieved
Kirschmann's Fourth Law
Kirschmann's Fourth Law states that the magnitude of simultaneous color contrast increases with the saturation of the inducing surround, but that the rate of increase reduces as saturation increases. Others since Kirschmann have agreed and disagreed. Here we show that the form of the relationship between simultaneous color contrast and inducer saturation depends on the method of measurement. Functions were measured by four methods: (i) asymmetric matching with a black surround, (ii) asymmetric matching with a surround metameric to equal energy white, (iii) dichoptic matching, and (iv) nulling an induced sinusoidal modulation. Results from the asymmetric matching conditions agreed with Kirschmann, whereas results from nulling and from dichoptic matching showed a more linear increase in simultaneous contrast with the saturation of the inducer. We conclude that the method certainly affects the conclusions reached, and that there may not be any "fair" way of measuring simultaneous contrast
CW and passively Q-switched double-clad planar waveguide lasers
Greater than 12 W of average output power have been generated from a diode pumped Yb:YAG cladding-pumped planar waveguide laser. The developed laser radiation is linearly polarized and diffraction limited in the guiding dimension. A slope efficiency of 0.5 W/W with a peak optical-optical conversion efficiency of 0.31 W/W is achieved. In a related structure, greater than 8 W of Q-switched average output power has been generated from a Nd:YAG cladding-pumped planar waveguide incorporating Cr:YAG passive Q-switch monolithically into the waveguide structure. Pulse widths of 3 nsec and PRFs as high as 80 kHz have been demonstrated. A slope efficiency of 0.28 W/W with a peak optical-optical conversion efficiency of 0.21 W/W is achieved
PySTACHIO: Python Single-molecule TrAcking stoiCHiometry Intensity and simulatiOn, a flexible, extensible, beginner-friendly and optimized program for analysis of single-molecule microscopy
As camera pixel arrays have grown larger and faster, and optical microscopy
techniques ever more refined, there has been an explosion in the quantity of
data acquired during routine light microcopy. At the single-molecule level,
analysis involves multiple steps and can rapidly become computationally
expensive, in some cases intractable on office workstations. Complex bespoke
software can present high activation barriers to entry for new users. Here, we
redevelop our quantitative single-molecule analysis routines into an optimized
and extensible Python program, with GUI and command-line implementations to
facilitate use on local machines and remote clusters, by beginners and advanced
users alike. We demonstrate that its performance is on par with previous MATLAB
implementations but runs an order of magnitude faster. We tested it against
challenge data and demonstrate its performance is comparable to
state-of-the-art analysis platforms. We show the code can extract fluorescence
intensity values for single reporter dye molecules and, using these, estimate
molecular stoichiometries and cellular copy numbers of fluorescently-labeled
biomolecules. It can evaluate 2D diffusion coefficients for the
characteristically short single-particle tracking data. To facilitate
benchmarking we include data simulation routines to compare different analysis
programs. Finally, we show that it works with 2-color data and enables
colocalization analysis based on overlap integration, to infer interactions
between differently labelled biomolecules. By making this freely available we
aim to make complex light microscopy single-molecule analysis more
democratized
Changes in the trajectory of the radio jet in 0735+178?
We present multi-epoch 8.4 and 43 GHz Very Long Baseline Array images of the
BL Lac object 0735+178. The images confirm the presence of a twisted jet with
two sharp apparent bends of 90 within two milliarcseconds of the
core, resembling a helix in projection. The observed twisted geometry could be
the result of precession of the jet inlet, but is more likely produced by
pressure gradients in the external medium through which the jet propagates.
Quasi-stationary components are observed at the locations of the 90
bends, possibly produced by differential Doppler boosting. Identification of
components across epochs, since the earliest VLBI observations of this source
in 1979.2, proves difficult due to the sometimes large time gaps between
observations. One possible identification suggests the existence of
superluminal components following non--ballistic trajectories with velocities
up to . However, in images obtained after mid-1995,
components show a remarkable tendency to cluster near several jet positions,
suggesting a different scenario in which components have remained nearly
stationary in time at least since mid-1995. Comparison with the earlier
published data, covering more than 19 years of observations, suggests a
striking qualitative change in the jet trajectory sometime between mid-1992 and
mid-1995, with the twisted jet structure with stationary components becoming
apparent only at the later epochs. This would require a re-evaluation of the
physical parameters estimated for 0735+178, such as the observing viewing
angle, the plasma bulk Lorentz factor, and those deduced from these.Comment: 18 pages, 5 figures, accepted for publication in MNRA
Challenges influencing the safety of migrant workers in the construction industry: A qualitative study in Italy, Spain, and the UK
The construction industry is notoriously high risk for accidents, injuries, and deaths, particularly for non-national or migrant workers, who comprise a significant proportion of the workforce. This paper presents an international, qualitative study focused on exploring the challenges which influence the safety of migrant construction workers in Italy, Spain, and the UK. Based on a comprehensive review of the literature, we formulated two research questions about the challenges relating to safety that migrant workers face and the challenges to safety training effectively improving migrant workers’ safety behaviours. We present our template analysis of semi-structured interviews and focus groups with 88 participants from four occupational groups across all three countries. This identified commonalities and differences in interpretations of the primary challenges to migrant workers’ safety, amongst participants from the various occupational groups (workers, site supervisors, safety trainers and safety experts) in Italy, Spain, and the UK. These were associated with: increased use of subcontractors; dilution of safety standards down the supply chain; pressure to breach safety regulations on site; differing safety-related attitudes and behaviours due to national cultural differences, language barriers and issues relating to training (provision, delivery, language, content and transfer). Finally, we summarise the contributions and limitations of our study, arguing further interventions related to safety training are needed, along with ethnographic studies to explore how both macro-level and contextual factors affect safety outcomes for migrant construction workers
Star and Planet Formation with ALMA: an Overview
Submillimeter observations with ALMA will be the essential next step in our
understanding of how stars and planets form. Key projects range from detailed
imaging of the collapse of pre-stellar cores and measuring the accretion rate
of matter onto deeply embedded protostars, to unravelling the chemistry and
dynamics of high-mass star-forming clusters and high-spatial resolution studies
of protoplanetary disks down to the 1 AU scale.Comment: Invited review, 8 pages, 5 figures; to appear in the proceedings of
"Science with ALMA: a New Era for Astrophysics". Astrophysics & Space
Science, in pres
Use of high cost care among Veterans with comorbid mental illness and Alzheimer's Disease and related dementias
Introduction/Objective Alzheimer's Disease and Other Related Dementias (AD/ADRD) leads to frequent emergency department (ED) and inpatient use. Mental health symptoms among persons with AD/ADRD increases cognitive and functional disabilities and could contribute to these high rates of intensive health care use. The objective of this paper is to assess the relationship of mental illness on 12-month patterns in hospitalization and ED use among Veterans aged 65 and over with a new AD/ADRD diagnosis. Methods We used an existing dataset of administrative electronic health record data of Veterans with AD/ADRD from the US Veterans Health Administration linked with Medicare claims data from 2011-2015. We use multivariable logistic regression to examine the association between no pre-existing mental illness, pre-existing mental illness (e.g., major depressive disorder, generalized anxiety disorder, or post-traumatic stress disorder), and pre-existing severe mental illness-or SMI-(e.g., bipolar disorder, major depressive disorder with psychosis, or schizophrenia) and 12- month ED and hospitalization use and readmissions among Veterans who had an initial hospitalization visit. We estimated predicted probabilities, differential effect, and associated 95% confidence intervals. Results In our sample, 1.4% had SMI and 11% had non-SMI mental illness. The unadjusted percentage with inpatient and ED use was higher among Veterans with SMI (34% and 26%, respectively) and Veterans with non-SMI mental illness (20%, 16%) compared with Veterans without pre-existing mental illness (12%, 9%). Compared to individuals with no pre-existing mental illness, having a pre-existing mental illness (1.27 percentage points, 95% CI: 0.76, 1.78) and a pre-existing SMI (7.17 percentage points, 95% CI: 5.66, 8.69) were both associated with an increased likelihood of ED use. The same pattern was observed for any inpatient use (mental illness 2.18, 95% CI: 1.59, 2.77; SMI 9.91, 95% CI: 8.21, 11.61). Only preexisting SMI was associated higher hospitalization readmission. Discussion Pre-existing mental illness increases use of high cost, intensive health care and this association is higher of more severe mental health conditions. We also show that pre-existing mental illness exerts a unique influence, above and beyond other comorbidities, such as diabetes, on ED and inpatient visits. More needs to be done to increase recognition of the unique risks of this combination of health conditions and encourage strategies to address them. Developing, testing, and implementing comprehensive strategies that address the intersection of ADRD and mental illness is promising approach that requires more focused attention
- …