764 research outputs found
Ground Water Monitoring System and Procedures at Kin-Buc I Landfill Middlesex County New Jersey
37 pages (includes illustrations and map)
Laser-Assisted Removal of Aspirated Thumbtacks by Flexible Bronchoscopy
Background. Aspirated thumbtacks are difficult to extract as the sharp edge of the thumbtack often is well imbedded within bronchial wall and its removal is technically demanding and may cause complications such as bronchial mucosal tear and bronchial wall perforation. These sharp metal objects are commonly removed using rigid bronchoscopy since their removal through flexible bronchoscopy is considered to be dangerous.
Objectives. To describe a technique for removal of sharp aspirated metal objects employing laser through flexible bronchoscopy. Methods. We report two patients in whom a new technique for removal of sharp aspirated metal objects utilizing Nd-Yag laser flexible bronchoscopy was used. Results. Successful and uncomplicated removal of the aspirated thumbpack by flexible bronchoscopy under conscious sedation was accomplished in the two patients described. Both patients were discharged within 24 hours. Conclusions. In patients with aspirated thumbtack laser-assisted breakage of the object through flexible bronchoscopy may obviate the need for rigid bronchoscopy or thoracotomy
Raised erythrocyte creatine in patients with pulmonary arterial hypertension – Evidence for subclinical hemolysis
SummaryBackgroundPulmonary arterial hypertension (PAH) has been associated with hemolytic conditions such as sickle cell disease but the possible role of hemolysis in the pathogenesis or pathophysiology of other forms of PAH has not been studied. Erythrocyte lifespan is the gold-standard test of hemolysis and may be measured by assaying erythrocyte creatine (EC) levels. EC decreases as the erythrocyte ages, so patients with hemolysis have high EC levels.MethodsWe measured EC and other parameters of hemolysis in patients with idiopathic and connective tissue associated PAH and normal controls.ResultsIn patients with PAH (n = 40), EC levels were higher than in controls n = 30 (patients EC 1.72 mcmol/g HgB 95%CI[1.51, 1.96], controls EC 1.05 mcmol/g HgB [0.93, 1.19], p < 0.0001). High levels of EC correlated with worse 6 min walk (r = −0.42, p < 0.0001) and worse functional class (p = 0.002). Other indirect indices of hemolysis (total lactate dehydrogenase, red cell distribution width) were also increased in patients with PAH relative to controls.ConclusionsThere is evidence of subclinical hemolysis in patients with PAH, and higher levels of hemolysis are associated with poorer exercise capacity
Fluid and Diffusion Limits for Bike Sharing Systems
Bike sharing systems have rapidly developed around the world, and they are
served as a promising strategy to improve urban traffic congestion and to
decrease polluting gas emissions. So far performance analysis of bike sharing
systems always exists many difficulties and challenges under some more general
factors. In this paper, a more general large-scale bike sharing system is
discussed by means of heavy traffic approximation of multiclass closed queueing
networks with non-exponential factors. Based on this, the fluid scaled
equations and the diffusion scaled equations are established by means of the
numbers of bikes both at the stations and on the roads, respectively.
Furthermore, the scaling processes for the numbers of bikes both at the
stations and on the roads are proved to converge in distribution to a
semimartingale reflecting Brownian motion (SRBM) in a -dimensional box,
and also the fluid and diffusion limit theorems are obtained. Furthermore,
performance analysis of the bike sharing system is provided. Thus the results
and methodology of this paper provide new highlight in the study of more
general large-scale bike sharing systems.Comment: 34 pages, 1 figure
A theoretical and numerical study of a phase field higher-order active contour model of directed networks.
We address the problem of quasi-automatic extraction of directed networks, which have characteristic geometric features, from images. To include the necessary prior knowledge about these geometric features, we use a phase field higher-order active contour model of directed networks. The model has a large number of unphysical parameters (weights of energy terms), and can favour different geometric structures for different parameter values. To overcome this problem, we perform a stability analysis of a long, straight bar in order to find parameter ranges that favour networks. The resulting constraints necessary to produce stable networks eliminate some parameters, replace others by physical parameters such as network branch width, and place lower and upper bounds on the values of the rest. We validate the theoretical analysis via numerical experiments, and then apply the model to the problem of hydrographic network extraction from multi-spectral VHR satellite images
A Graph Theoretic Approach for Object Shape Representation in Compositional Hierarchies Using a Hybrid Generative-Descriptive Model
A graph theoretic approach is proposed for object shape representation in a
hierarchical compositional architecture called Compositional Hierarchy of Parts
(CHOP). In the proposed approach, vocabulary learning is performed using a
hybrid generative-descriptive model. First, statistical relationships between
parts are learned using a Minimum Conditional Entropy Clustering algorithm.
Then, selection of descriptive parts is defined as a frequent subgraph
discovery problem, and solved using a Minimum Description Length (MDL)
principle. Finally, part compositions are constructed by compressing the
internal data representation with discovered substructures. Shape
representation and computational complexity properties of the proposed approach
and algorithms are examined using six benchmark two-dimensional shape image
datasets. Experiments show that CHOP can employ part shareability and indexing
mechanisms for fast inference of part compositions using learned shape
vocabularies. Additionally, CHOP provides better shape retrieval performance
than the state-of-the-art shape retrieval methods.Comment: Paper : 17 pages. 13th European Conference on Computer Vision (ECCV
2014), Zurich, Switzerland, September 6-12, 2014, Proceedings, Part III, pp
566-581. Supplementary material can be downloaded from
http://link.springer.com/content/esm/chp:10.1007/978-3-319-10578-9_37/file/MediaObjects/978-3-319-10578-9_37_MOESM1_ESM.pd
Application of the cross-entropy method to the buffer allocation problem in a simulation-based environment
The buffer allocation problem (BAP) is a well-known difficult problem in the design of production lines. We present a stochastic algorithm for solving the BAP, based on the cross-entropy method, a new paradigm for stochastic optimization. The algorithm involves the following iterative steps: (a) the generation of buffer allocations according to a certain random mechanism, followed by (b) the modification of this mechanism on the basis of cross-entropy minimization. Through various numerical experiments we demonstrate the efficiency of the proposed algorithm and show that the method can quickly generate (near-)optimal buffer allocations for fairly large production lines
Towards on-chip tunable nanolasers based on optomechanical zipper cavities
Work towards semiconductor nanolasers at λ = 1.3 μm in optomechanically coupled one
dimensional photonic-crystal cavities is presented. Optical mode spectroscopy and on-chip tuning capability
based on capacitive actuation is developed. Experimental and theoretical results are presented
Forced-unfolding and force-quench refolding of RNA hairpins
Using coarse-grained model we have explored forced-unfolding of RNA hairpin
as a function of and the loading rate (). The simulations and
theoretical analysis have been done without and with the handles that are
explicitly modeled by semiflexible polymer chains. The mechanisms and time
scales for denaturation by temperature jump and mechanical unfolding are vastly
different. The directed perturbation of the native state by results in a
sequential unfolding of the hairpin starting from their ends whereas thermal
denaturation occurs stochastically. From the dependence of the unfolding rates
on and we show that the position of the unfolding transition state
(TS) is not a constant but moves dramatically as either or is
changed. The TS movements are interpreted by adopting the Hammond postulate for
forced-unfolding. Forced-unfolding simulations of RNA, with handles attached to
the two ends, show that the value of the unfolding force increases (especially
at high pulling speeds) as the length of the handles increases. The pathways
for refolding of RNA from stretched initial conformation, upon quenching
to the quench force , are highly heterogeneous. The refolding times, upon
force quench, are at least an order of magnitude greater than those obtained by
temperature quench. The long -dependent refolding times starting from
fully stretched states are analyzed using a model that accounts for the
microscopic steps in the rate limiting step which involves the trans to gauche
transitions of the dihedral angles in the GAAA tetraloop. The simulations with
explicit molecular model for the handles show that the dynamics of force-quench
refolding is strongly dependent on the interplay of their contour length and
the persistence length, and the RNA persistence length.Comment: 42 pages, 15 figures, Biophys. J. (in press
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