1,190 research outputs found
Compliant and flexible business processes with business rules.
When modeling business processes, we often implicitly think of internal business policies and external regulations. Yet to date, little attention is paid to avoid hard-coding policies and regulations directly in control-flow based process models. The standpoint of this analysis is the role of business rule modeling in achieving business process flexibility. In particular, it is argued that flexible business process models require business rules as a declarative formalism to capture the semantics of policy and regulation. Four kinds of business rules can be used as a starting point to generate less complex control-flow-based business process models. It is shown that these different kinds of business rules relate to different perspectives in the taxonomy of business process flexibility.
Revised research about chaotic dynamics in Manko et al. spacetime
A recent work by Dubeibe et al. [Phys. Rev. D 75, 023008 (2007)] stated that
chaos phenomenon of test particles in gravitational field of rotating neutron
stars which are described by Manko, Sanabria-Gomez, and Manko (Manko et al.)
metric can only occur when the stars have oblate deformation. But the chaotic
motions they found are limited in a very narrow zone which is very close to the
center of the massive bodies. This paper argues that this is impossible because
the region is actually inside of the stars, so the motions cannot exist at this
place. In this paper, we scan all parameters space and find chaos and unstable
fixed points outside of stars with big mass-quadrupole moments. The
calculations show that chaos can only occur when the stars have prolate
deformation. Because real deformation of stars should be oblate, all orbits of
test particles around the rotating neutron stars described by Manko et al.
solutions are regular. The case of nonzero dipolar magnetic moment has also
been taken into account in this study.Comment: 6 pages, 5 figure
Non-exponential hydrodynamical growth in density-stratified thin Keplerian discs
The short time evolution of three dimensional small perturbations is studied.
Exhibiting spectral asymptotic stability, thin discs are nonetheless shown to
host intensive hydrodynamical activity in the shape of non modal growth of
initial small perturbations. Two mechanisms that lead to such behavior are
identified and studied, namely, non-resonant excitation of vertically confined
sound waves by stable planar inertia-coriolis modes that results in linear
growth with time, as well as resonant coupling of those two modes that leads to
a quadratic growth of the initial perturbations. It is further speculated that
the non modal growth can give rise to secondary strato-rotational instabilities
and thus lead to a new route to turbulence generation in thin discs
BROCKMAN: deciphering variance in epigenomic regulators by k-mer factorization
Background: Variation in chromatin organization across single cells can help shed important light on the mechanisms controlling gene expression, but scale, noise, and sparsity pose significant challenges for interpretation of single cell chromatin data. Here, we develop BROCKMAN (Brockman Representation Of Chromatin by K-mers in Mark-Associated Nucleotides), an approach to infer variation in transcription factor (TF) activity across samples through unsupervised analysis of the variation in DNA sequences associated with an epigenomic mark. Results: BROCKMAN represents each sample as a vector of epigenomic-mark-associated DNA word frequencies, and decomposes the resulting matrix to find hidden structure in the data, followed by unsupervised grouping of samples and identification of the TFs that distinguish groups. Applied to single cell ATAC-seq, BROCKMAN readily distinguished cell types, treatments, batch effects, experimental artifacts, and cycling cells. We show that each variable component in the k-mer landscape reflects a set of co-varying TFs, which are often known to physically interact. For example, in K562 cells, AP-1 TFs were central determinant of variability in chromatin accessibility through their variable expression levels and diverse interactions with other TFs. We provide a theoretical basis for why cooperative TF binding – and any associated epigenomic mark – is inherently more variable than non-cooperative binding. Conclusions: BROCKMAN and related approaches will help gain a mechanistic understanding of the trans determinants of chromatin variability between cells, treatments, and individuals. Keywords: Single-cell, Epigenome, Chromatin, scATAC-seq, K-mer, N-gram, Factorization, Decomposition, Clustering,
Transcription factorNational Human Genome Research Institute (U.S.) (Centers of Excellence in Genomic Science Grant)Howard Hughes Medical Institute (Centers of Excellence in Genomic Science Grant
What is essential? – a pilot survey on views about the requirements metamodel of reqT.org
[Context & motivation] This research preview paper presents ongoing work on the metamodel of a free software requirements modeling tool called reqT that is developed in an educational context. The work aims to make an initial validation of a survey instrument that elicits views on the metamodel of the reqT tool, which aims to engage computer science students in Requirements Engineering (RE) through an open source DSL embedded in the Scala programming language. [Question] The research question is: Which RE concepts are essential to include in the metamodel for a requirements engineering tool in an educational context? [Principal ideas] A survey instrument is developed, with a list of 92 concepts (49 entities, 15 relations and 28 attributes) and a set of questions for each concept, to elicit the respondents’ views on the usage and interpretation of each concept. [Contribution] The survey is initially validated in a pilot study involving 14 Swedish RE scholars as subjects. The survey results indicate that the survey is feasible. The analysis of the responses suggest that many of the concepts in the metamodel are used frequently by the respondents and there is a large degree of agreement among the respondents about the meaning of the concepts. The results are encouraging for future work on empirical validation of the relevance of the reqT metamodel
Quantum algorithm for the Boolean hidden shift problem
The hidden shift problem is a natural place to look for new separations
between classical and quantum models of computation. One advantage of this
problem is its flexibility, since it can be defined for a whole range of
functions and a whole range of underlying groups. In a way, this distinguishes
it from the hidden subgroup problem where more stringent requirements about the
existence of a periodic subgroup have to be made. And yet, the hidden shift
problem proves to be rich enough to capture interesting features of problems of
algebraic, geometric, and combinatorial flavor. We present a quantum algorithm
to identify the hidden shift for any Boolean function. Using Fourier analysis
for Boolean functions we relate the time and query complexity of the algorithm
to an intrinsic property of the function, namely its minimum influence. We show
that for randomly chosen functions the time complexity of the algorithm is
polynomial. Based on this we show an average case exponential separation
between classical and quantum time complexity. A perhaps interesting aspect of
this work is that, while the extremal case of the Boolean hidden shift problem
over so-called bent functions can be reduced to a hidden subgroup problem over
an abelian group, the more general case studied here does not seem to allow
such a reduction.Comment: 10 pages, 1 figur
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