1,525,813 research outputs found
Compound oxidized styrylphosphine
A process is described for preparing flame resistant, nontoxic vinyl polymers which contain phosphazene groups and which do not emit any toxic or corrosive products when they are oxidatively degraded. Homopolymers, copolymers, and terpolymers of a styrene based monomer are prepared by polymerizing at least one oxidized styrylphosphine monomer from a group of organic azides, or by polymerizing p-diphenylphosphinestyrene and then oxidizing that monomer with an organoazide from the group of (C6H5)2P(O)N3, (C6H5O)2P(O)N3, (C6H5)2C3N3(N3), and C6H5C3N3(N3)2. Copolymers can also be prepared by copolymerizing styrene with at least one oxidized styrylphosphine monomer
Compound-Specific Radiocarbon Analysis by Elemental Analyzer–Accelerator Mass Spectrometry: Precision and Limitations
[EN]We examine instrumental and methodological capabilities for microscale (10−50μg of C) radiocarbon analysisof individual compounds in the context of paleoclimate and paleoceanography applications, for which relatively high-precisionmeasurements are required. An extensive suite of data for14C-free and modern reference materials processed using differentmethods and acquired using an elemental-analyzer−accelerator-mass-spectrometry (EA-AMS) instrumental setup at ETHZurich was compiled to assess the reproducibility of specific isolation procedures. In order to determine the precision, accuracy,and reproducibility of measurements on processed compounds, we explore the results of both reference materials and threeclasses of compounds (fatty acids, alkenones, and amino acids) extracted from sediment samples. We utilize a MATLAB codedeveloped to systematically evaluate constant-contamination-model parameters, which in turn can be applied to measurementsof unknown process samples. This approach is computationally reliable and can be used for any blank assessment of small-sizeradiocarbon samples. Our results show that a conservative lower estimate of the sample sizes required to produce relativelyhigh-precision14C data (i.e., with acceptable errors of 0.5, a precision of 2% can be achieved for alkenone and fatty acid samples containing≥15 and 10μg of C, respectivel
Compound-specific isotope analysis of diesel fuels in a forensic investigation
Compound-specific isotope analysis (CSIA) offers great potential as a tool to provide chemical evidence in a forensic investigation. Many attempts to trace environmental oil spills were successful where isotopic values were particularly distinct. However, difficulties arise when a large data set is analyzed and the isotopic differences between samples are subtle. In the present study, discrimination of diesel oils involved in a diesel theft case was carried out to infer the relatedness of the samples to potential source samples. This discriminatory analysis used a suite of hydrocarbon diagnostic indices, alkanes, to generate carbon and hydrogen isotopic data of the compositions of the compounds which were then processed using multivariate statistical analyses to infer the relatedness of the data set. The results from this analysis were put into context by comparing the data with the δ13C and δ2H of alkanes in commercial diesel samples obtained from various locations in the South Island of New Zealand. Based on the isotopic character of the alkanes, it is suggested that diesel fuels involved in the diesel theft case were distinguishable. This manuscript shows that CSIA when used in tandem with multivariate statistical analysis provide a defensible means to differentiate and source-apportion qualitatively similar oils at the molecular level. This approach was able to overcome confounding challenges posed by the near single-point source of origin, i.e., the very subtle differences in isotopic values between the samples
Fissibility of compound nuclei
Collisions between Cm and Ca are systematically investigated
by time-dependent density functional calculations with evaporation
prescription. Depending on the incident energy and impact parameter, fusion,
deep-inelastic and fission events are expected to appear. In this paper, a
microscopic method of calculating the fissibility of compound nuclei is
presented.Comment: To appear in the EXON 2012 Proceedings in Int. J. Mod. Phys.
Compound droplets on fibers
Droplets on fibers have been extensively studied in the recent years.
Although the equilibrium shapes of simple droplets on fibers are well
established, the situation becomes more complex for compound fluidic systems.
Through experimental and numerical investigations, we show herein that compound
droplets can be formed on fibers and that they adopt specific geometries. We
focus on the various contact lines formed at the meeting of the different
phases and we study their equilibrium state. It appears that, depending on the
surface tensions, the triple contact lines can remain separate or merge
together and form quadruple lines. The nature of the contact lines influences
the behavior of the compound droplets on fibers. Indeed, both experimental and
numerical results show that, during the detachment process, depending on
whether the contact lines are triple or quadruple, the characteristic length is
the inner droplet radius or the fiber radius
Hierarchical Compound Poisson Factorization
Non-negative matrix factorization models based on a hierarchical
Gamma-Poisson structure capture user and item behavior effectively in extremely
sparse data sets, making them the ideal choice for collaborative filtering
applications. Hierarchical Poisson factorization (HPF) in particular has proved
successful for scalable recommendation systems with extreme sparsity. HPF,
however, suffers from a tight coupling of sparsity model (absence of a rating)
and response model (the value of the rating), which limits the expressiveness
of the latter. Here, we introduce hierarchical compound Poisson factorization
(HCPF) that has the favorable Gamma-Poisson structure and scalability of HPF to
high-dimensional extremely sparse matrices. More importantly, HCPF decouples
the sparsity model from the response model, allowing us to choose the most
suitable distribution for the response. HCPF can capture binary, non-negative
discrete, non-negative continuous, and zero-inflated continuous responses. We
compare HCPF with HPF on nine discrete and three continuous data sets and
conclude that HCPF captures the relationship between sparsity and response
better than HPF.Comment: Will appear on Proceedings of the 33 rd International Conference on
Machine Learning, New York, NY, USA, 2016. JMLR: W&CP volume 4
Metadata for Compound Objects
This training introduced the large-scale approach to describing multi-page digital compound objects. It was developed to disambiguate and clarify the new approach of describing compound objects in Project client/ContentDm. The training focused on important metadata fields, provided practical examples and instructed student assistants and staff how to apply the new rules consistently across all collections. The training session was followed by hands-on activities and discussion
Compound Poisson and signed compound Poisson approximations to the Markov binomial law
Compound Poisson distributions and signed compound Poisson measures are used
for approximation of the Markov binomial distribution. The upper and lower
bound estimates are obtained for the total variation, local and Wasserstein
norms. In a special case, asymptotically sharp constants are calculated. For
the upper bounds, the smoothing properties of compound Poisson distributions
are applied. For the lower bound estimates, the characteristic function method
is used.Comment: Published in at http://dx.doi.org/10.3150/09-BEJ246 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
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