8,286 research outputs found
Investigation of Metal and Organic Contaminant Distributions and Sedimentation Rates in Backwater Lakes along the Illinois River
Systematic sub-sampling of sediment cores in sections of uniform thickness is necessary
in order to evaluate historic changes in sediment quality, to determine the vertical extent
of contamination, and to measure sedimentation rates. With these objectives in mind,
fourteen sediment cores were collected during March 2002 using the Illinois State Water
Survey vibracorer. Concentrations of metals and total organic carbon were measured
using standard techniques. Concentrations of chlorinated pesticides, phenolic compounds,
polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were
measured by gas chromatography/mass spectrometry (GC-MS). The concentrations of
chlorinated pesticides, phenolic compounds and polychlorinated biphenyls (PCBs) were
below the method detection limit in all sediment samples analyzed. However, there was
a wide range in concentrations of polycyclic aromatic hydrocarbons (PAHs) which were
detected in all sediment samples. Also, a wide range of metal concentrations was noted
in the sediments evaluated. Lower concentrations of metals were found in the upper 0.5
m of sediment but concentrations were elevated at depths ranging from 1.0 m to 1.5 m.
Sedimentation rates were estimated using cesium-137 radiometric dating on 14
vibracores. Sedimentation rates range from < 0.1 to 1.9 cm/yr, with an average of 0.9
cm/yr. These rates are comparable to those reported in previous studies.Illinois Sustainable Technology Centerpublished or submitted for publicationis peer reviewe
Mobilizing Public Will For Social Change
Examines the theory and strategies of "public will" campaigns and offers tangible criteria for their evaluation. It provides a rich inventory of strategies for use in mobilizing the public will through an integration of models of agenda building, social problem construction, issues management, social movements, media advocacy, and social capital. In addition, the paper provides cases and examples of public will campaigns directed at various social problems, along with criteria for evaluating these campaigns at various stages of a social problem's life cycle
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Characteristics of successful interventions to reduce turnover and increase retention of early career nurses: a systematic review
Background
nurse shortages have been identified as central to workforce issues in healthcare systems globally and although interventions to increase the nursing workforce have been implemented, nurses leaving their roles, particularly in the first year after qualification, present a significant barrier to building the nurse workforce.
Objective
to evaluate the characteristics of successful interventions to promote retention and reduce turnover of early career nurses.
Design
this is a systematic review
Data sources
Online databases including Academic Search Complete, Medline, Health Policy reference Centre, EMBASE, Psychinfo, CINAHL and the Cochran Library were searched to identify relevant publications in English published between 2001 and April 2018. Studies included evaluated an intervention to increase retention or reduce turnover and used turnover or retention figures as a measure.
Review methods
The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies were quality-assessed using the Joanna Briggs Institute Critical Appraisal tools for Quasi Experimental and Randomised Controlled Trials. Retention/turnover data were used to guide the comparison between studies and appropriate measures of central tendency and dispersion were calculated and presented, based on the normality of the data.
Results
A total of 11, 656 papers were identified, of which 53 were eligible studies. A wide variety of interventions and components within those interventions were identified to improve nurse retention. Promising interventions appear to be either internship/residency programmes or orientation/transition to practice programmes, lasting between 27-52 weeks, with a teaching and preceptor and mentor component.
Conclusions
Methodological issues impacted on the extent to which conclusions could be drawn, even though a large number of studies were identified. Future research should focus on standardising the reporting of interventions and outcome measures used to evaluate these interventions and carrying out further research with rigorous methodology. Clinical practice areas are recommended to assess their current interventions against the identified criteria to guide development of their effectiveness. Evaluations of cost-effectiveness are considered an important next step to maximise return on investment
The Domestication and Migration of Zea mays L. in Association with Holocene Climatic Variance
Maize is known to have originated in Mesoamerica from which it spread north and south, adapting to many varied climatic and environmental conditions. This study details the origin of the species Zea mays L. The teosinte hypothesis and the concepts of seasonality and scheduling are employed to discuss the domestication of maize by means of human selection. This information is used to highlight the basic circumstances necessary for maize agriculture to be adopted by a human population. Furthermore, climate is examined through the minimum and ideal environmental conditions needed for the successful growth of maize. Environmental cues play a profound role in the phenotypic characteristics a species exhibits; therefore Holocene climactic events are examined in areas with extensive evidence of maize domestication. The minimum requirements for maize growth are compared against the actual conditions during periods of significant climatic change (Little Ice Age, Medieval Warm Period, etc.). Through comparing the ideal versus realized conditions over time, a model for the diffusion of maize from Mesoamerica into North America, with a particular focus on the Southwest and Ohio Valley, is developed
Measuring situation awareness in complex systems: Comparison of measures study
Situation Awareness (SA) is a distinct critical commodity for teams working in complex industrial systems and its measurement is a key provision in system, procedural and training design efforts. This article describes a study that was undertaken in order to compare three different SA measures (a freeze probe recall approach, a post trial subjective rating approach and a critical incident interview technique) when used to assess participant SA during a military planning task. The results indicate that only the freeze probe recall method produced a statistically significant correlation with performance on the planning task and also that there was no significant correlation between the three methods, which suggests that they were effectively measuring different things during the trials. In conclusion, the findings, whilst raising doubts over the validity of post trial subjective rating and interview-based approaches, offer validation evidence for the use of freeze probe recall approaches to measure SA. The findings are subsequently discussed with regard to their implications for the future measurement of SA in complex collaborative systems
3D printing dimensional calibration shape: Clebsch Cubic
3D printing and other layer manufacturing processes are challenged by
dimensional accuracy. Several techniques are used to validate and calibrate
dimensional accuracy through the complete building envelope. The validation
process involves the growing and measuring of a shape with known parameters.
The measured result is compared with the intended digital model. Processes with
the risk of deformation after time or post processing may find this technique
beneficial. We propose to use objects from algebraic geometry as test shapes. A
cubic surface is given as the zero set of a 3rd degree polynomial with 3
variables. A class of cubics in real 3D space contains exactly 27 real lines.
We provide a library for the computer algebra system Singular which, from 6
given points in the plane, constructs a cubic and the lines on it. A surface
shape derived from a cubic offers simplicity to the dimensional comparison
process, in that the straight lines and many other features can be analytically
determined and easily measured using non-digital equipment. For example, the
surface contains so-called Eckardt points, in each of which three of the lines
intersect, and also other intersection points of pairs of lines. Distances
between these intersection points can easily be measured, since the points are
connected by straight lines. At all intersection points of lines, angles can be
verified. Hence, many features distributed over the build volume are known
analytically, and can be used for the validation process. Due to the thin shape
geometry the material required to produce an algebraic surface is minimal. This
paper is the first in a series that proposes the process chain to first define
a cubic with a configuration of lines in a given print volume and then to
develop the point cloud for the final manufacturing. Simple measuring
techniques are recommended.Comment: 8 pages, 1 figure, 1 tabl
High-frequency ultrasonic speckle velocimetry in sheared complex fluids
High-frequency ultrasonic pulses at 36 MHz are used to measure velocity
profiles in a complex fluid sheared in the Couette geometry. Our technique is
based on time-domain cross-correlation of ultrasonic speckle signals
backscattered by the moving medium. Post-processing of acoustic data allows us
to record a velocity profile in 0.02--2 s with a spatial resolution of 40
m over 1 mm. After a careful calibration using a Newtonian suspension, the
technique is applied to a sheared lyotropic lamellar phase seeded with
polystyrene spheres of diameter 3--10 m. Time-averaged velocity profiles
reveal the existence of inhomogeneous flows, with both wall slip and shear
bands, in the vicinity of a shear-induced ``layering'' transition. Slow
transient regimes and/or temporal fluctuations can also be resolved and exhibit
complex spatio-temporal flow behaviors with sometimes more than two shear
bands.Comment: 15 pages, 18 figures, submitted to Eur. Phys. J. A
Information requirements for supersonic transport operation Final report
Effects of meteorological parameters and instrument errors on vertical flight performance of supersonic transport
RECORDS OF THE SUBANTARCTIC FUR SEAL ARCTOCEPHALUS TROPICALIS FROM RODRIGUES AND MAURITIUS, INDIAN OCEAN
A juvenile Subantarctic fur seal Arctocephalus tropicalis was recorded on the Indian Ocean island of Rodrigues and two were seen on Mauritius. These records are at least 2 500 km from the closest breeding colony (Amsterdam Island) and are the most easterly by some 1 800 km of all previous records of vagrants of this species.Afr. J. mar. Sci. 25: 403–40
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