869 research outputs found
Mercury in the environment
Problems in assessing mercury concentrations in environmental materials are discussed. Data for situations involving air, water, rocks, soils, sediments, sludges, fossil fuels, plants, animals, foods, and man are drawn together and briefly evaluated. Details are provided regarding the toxicity of mercury along with tentative standards and guidelines for mercury in air, drinking water, and food
F100(3) parallel compressor computer code and user's manual
The Pratt & Whitney Aircraft multiple segment parallel compressor model has been modified to include the influence of variable compressor vane geometry on the sensitivity to circumferential flow distortion. Further, performance characteristics of the F100 (3) compression system have been incorporated into the model on a blade row basis. In this modified form, the distortion's circumferential location is referenced relative to the variable vane controlling sensors of the F100 (3) engine so that the proper solution can be obtained regardless of distortion orientation. This feature is particularly important for the analysis of inlet temperature distortion. Compatibility with fixed geometry compressor applications has been maintained in the model
On 2-switches and isomorphism classes
A 2-switch is an edge addition/deletion operation that changes adjacencies in
the graph while preserving the degree of each vertex. A well known result
states that graphs with the same degree sequence may be changed into each other
via sequences of 2-switches. We show that if a 2-switch changes the isomorphism
class of a graph, then it must take place in one of four configurations. We
also present a sufficient condition for a 2-switch to change the isomorphism
class of a graph. As consequences, we give a new characterization of matrogenic
graphs and determine the largest hereditary graph family whose members are all
the unique realizations (up to isomorphism) of their respective degree
sequences.Comment: 11 pages, 6 figure
APPARATUS FOR DETERMINING LINEAR THERMAL EXPANSIONS OF MATERIALS IN VACUUM OR CONTROLLED ATMOSPHERE
An apparatus for determining linear thermal expansion data up to 1350 deg C for materials that cannot be heated in air is described. Expansion is not measured directly, but is derived from the differential expansion between the material being tested and the materials of construction of the dilatometer. The apparatus is calibrated against published data on the linear thermal expansion of both fused silica and polycrystalline tungsten metal. It can be operated either as a high-vacuum or as a controlled-atmosphere apparatus. Recording of data is either fully automatic or manual. The percentage error is believed to be no greater than plus or minus 0.1 to 0.2%. Original data for linear thermal expansion of materials such as hot-pressed BeO, hafnium-free ZrC/sub 2/, zirconium-free HfO/sub 2/, INOR-8 alloy, siliconized silicon carbide, uranium dioxide, compositions of Be + BeO, and samples of CS 312 graphite, boron nitride, and tungsten metal. (auth
ClassCut for Unsupervised Class Segmentation
Abstract. We propose a novel method for unsupervised class segmentation on a set of images. It alternates between segmenting object instances and learning a class model. The method is based on a segmentation energy defined over all images at the same time, which can be optimized efficiently by techniques used before in interactive segmentation. Over iterations, our method progressively learns a class model by integrating observations over all images. In addition to appearance, this model captures the location and shape of the class with respect to an automatically determined coordinate frame common across images. This frame allows us to build stronger shape and location models, similar to those used in object class detection. Our method is inspired by interactive segmentation methods [1], but it is fully automatic and learns models characteristic for the object class rather than specific to one particular object/image. We experimentally demonstrate on the Caltech4, Caltech101, and Weizmann horses datasets that our method (a) transfers class knowledge across images and this improves results compared to segmenting every image independently; (b) outperforms Grabcut [1] for the task of unsupervised segmentation; (c) offers competitive performance compared to the state-of-the-art in unsupervised segmentation and in particular it outperforms the topic model [2].
Partitioning SKA Dataflows for Optimal Graph Execution
Optimizing data-intensive workflow execution is essential to many modern
scientific projects such as the Square Kilometre Array (SKA), which will be the
largest radio telescope in the world, collecting terabytes of data per second
for the next few decades. At the core of the SKA Science Data Processor is the
graph execution engine, scheduling tens of thousands of algorithmic components
to ingest and transform millions of parallel data chunks in order to solve a
series of large-scale inverse problems within the power budget. To tackle this
challenge, we have developed the Data Activated Liu Graph Engine (DALiuGE) to
manage data processing pipelines for several SKA pathfinder projects. In this
paper, we discuss the DALiuGE graph scheduling sub-system. By extending
previous studies on graph scheduling and partitioning, we lay the foundation on
which we can develop polynomial time optimization methods that minimize both
workflow execution time and resource footprint while satisfying resource
constraints imposed by individual algorithms. We show preliminary results
obtained from three radio astronomy data pipelines.Comment: Accepted in HPDC ScienceCloud 2018 Worksho
Reducing Occupational Distress in Veterinary Medicine Personnel with Acceptance and Commitment Training: A Pilot Study
Aims
To determine whether an educational programme targeting the reaction of veterinary personnel to difficult client interactions reduced burden transfer, stress and burnout in veterinary staff.
Methods
Employees of three small-animal veterinary hospitals in the south-western United States of America were recruited and randomised to intervention (educational programme; n = 16) or control (no intervention; n = 18) groups. Participants of this randomised, parallel arms trial completed pre-programme assessment including the Burden Transfer Inventory (BTI), Perceived Stress Scale, and Copenhagen Burnout Inventory. Assessment was followed by two, group-format educational sessions, based on acceptance and commitment training, tailored to reducing reactivity to difficult veterinary client interactions (intervention group only). After training was completed, both groups were assessed using the same measures and the intervention participants provided use and acceptability ratings.
Results
Intervention participants rated the programme as useful and appropriate, and reported that programme techniques were used a median of 43 (min 9, max 68) times during the 2 weeks prior to retesting. Relative to pre-programme scores, median post-programme scores for reaction (subscore of BTI) to difficult client interactions decreased in the intervention group (33 vs. 54; p = 0.047), but not in the control group (51 vs. 59; p = 0.210). Changes in median scores for stress and burnout from pre- to post-programme were non-significant for both groups.
Conclusions
This pilot and feasibility trial showed high rates of acceptability and use by participants, as well as promising reductions in burden transfer. A larger scale clinical trial with follow-up at extended time points is needed to more fully examine the efficacy of this novel programme
Minimal Obstructions for Partial Representations of Interval Graphs
Interval graphs are intersection graphs of closed intervals. A generalization
of recognition called partial representation extension was introduced recently.
The input gives an interval graph with a partial representation specifying some
pre-drawn intervals. We ask whether the remaining intervals can be added to
create an extending representation. Two linear-time algorithms are known for
solving this problem.
In this paper, we characterize the minimal obstructions which make partial
representations non-extendible. This generalizes Lekkerkerker and Boland's
characterization of the minimal forbidden induced subgraphs of interval graphs.
Each minimal obstruction consists of a forbidden induced subgraph together with
at most four pre-drawn intervals. A Helly-type result follows: A partial
representation is extendible if and only if every quadruple of pre-drawn
intervals is extendible by itself. Our characterization leads to a linear-time
certifying algorithm for partial representation extension
Deepening trochleoplasty with a thick osteochondral flap for patellar instability:Clinical and functional outcomes at mean 6 year follow-up
Background: In patients with patellar instability and severe trochlear dysplasia, trochleoplasty has become increasingly used as part of the surgical management. Hypothesis: Deepening trochleoplasty for severe dysplasia in patellofemoral instability improves function and increases sports participation. Study Design: Case series; Level of evidence, 4. Methods: Between 1995and 2010 the thick-flap deepening trochleoplasty was performed in 90 patients (107 knees) with severe trochlear dysplasia. Data was collected prospectively pre-operatively, at 6 weeks and 1-year follow-up. The patients were surveyed retrospectively to determine the clinical and functional outcomes including sports and exercise participation at a minimum of 2 years, with complete data available in 92%. Results: With a minimum follow-up of 2 years, average of 6 years (range 2 – 19 years). The Kujala score had a median and interquartile range (IQR) of 63 (47-75) pre-operatively rising to 79 (68-91) at 1 year follow-up and 84 (73-92) at final follow-up (p< 0.05). Seventy-two per cent were satisfied with their knee function at 1 year follow-up rising to 79% at final follow-up (p <0.0001). Sports and exercise participation increased from 36 patients (40%) pre-operatively to 60 (67%) at final follow-up. The numbers involved in competitions increased slightly from 10 (11%) to 11 (12%). Of those sports that involved twisting (e.g. soccer, cricket, badminton), the proportion of patients participation increased from 16 (18%) to 22 (24%), whereas in non-twisting sports (e.g. running, swimming, cycling) it increased from 24 (27%) to 47 (52%) of whom 14 (16%) used walking as exercise. Conclusion: The thick-flap deepening trochleoplasty improves the clinical and functional outcomes for patients with symptomatic patellar instability with severe trochlear dysplasia. These results improve over time and beyond the 1 year clinical follow-up. However trochleoplasty does not lead to a significant improvement in sports participation at a competitive level. It does improve the sports and exercise patient participation, principally in non-twisting sports activities
Labels direct infants’ attention to commonalities during novel category learning
Recent studies have provided evidence that labeling can influence the outcome of infants’ visual categorization. However, what exactly happens during learning remains unclear. Using eye-tracking, we examined infants’ attention to object parts during learning. Our analysis of looking behaviors during learning provide insights going beyond merely observing the learning outcome. Both labeling and non-labeling phrases facilitated category formation in 12-month-olds but not 8-month-olds (Experiment 1). Non-linguistic sounds did not produce this effect (Experiment 2). Detailed analyses of infants’ looking patterns during learning revealed that only infants who heard labels exhibited a rapid focus on the object part successive exemplars had in common. Although other linguistic stimuli may also be beneficial for learning, it is therefore concluded that labels have a unique impact on categorization
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