1,497 research outputs found
Role-similarity based functional prediction in networked systems: Application to the yeast proteome
We propose a general method to predict functions of vertices where: 1. The
wiring of the network is somehow related to the vertex functionality. 2. A
fraction of the vertices are functionally classified. The method is influenced
by role-similarity measures of social network analysis. The two versions of our
prediction scheme is tested on model networks were the functions of the
vertices are designed to match their network surroundings. We also apply these
methods to the proteome of the yeast Saccharomyces cerevisiae and find the
results compatible with more specialized methods
Expression of CD226 is associated to but not required for NK cell education
AbstractDNAX accessory molecule-1 (DNAM-1, also known as CD226) is an activating receptor expressed on subsets of natural killer (NK) and T cells, interacts with its ligands CD155 or CD112, and has co-varied expression with inhibitory receptors. Since inhibitory receptors control NK-cell activation and are necessary for MHC-I-dependent education, we investigated whether DNAM-1 expression is also involved in NK-cell education. Here we show an MHC-I-dependent correlation between DNAM-1 expression and NK-cell education, and an association between DNAM-1 and NKG2A that occurs even in MHC class I deficient mice. DNAM-1 is expressed early during NK-cell development, precedes the expression of MHC-I-specific inhibitory receptors, and is modulated in an education-dependent fashion. Cd226−/− mice have missing self-responses and NK cells with a normal receptor repertoire. We propose a model in which NK-cell education prevents or delays downregulation of DNAM-1. This molecule endows educated NK cells with enhanced effector functions but is dispensable for education.</jats:p
Discrete concavity and the half-plane property
Murota et al. have recently developed a theory of discrete convex analysis
which concerns M-convex functions on jump systems. We introduce here a family
of M-concave functions arising naturally from polynomials (over a field of
generalized Puiseux series) with prescribed non-vanishing properties. This
family contains several of the most studied M-concave functions in the
literature. In the language of tropical geometry we study the tropicalization
of the space of polynomials with the half-plane property, and show that it is
strictly contained in the space of M-concave functions. We also provide a short
proof of Speyer's hive theorem which he used to give a new proof of Horn's
conjecture on eigenvalues of sums of Hermitian matrices.Comment: 14 pages. The proof of Theorem 4 is corrected
Are Opinions Based on Science: Modelling Social Response to Scientific Facts
As scientists we like to think that modern societies and their members base
their views, opinions and behaviour on scientific facts. This is not
necessarily the case, even though we are all (over-) exposed to information
flow through various channels of media, i.e. newspapers, television, radio,
internet, and web. It is thought that this is mainly due to the conflicting
information on the mass media and to the individual attitude (formed by
cultural, educational and environmental factors), that is, one external factor
and another personal factor. In this paper we will investigate the dynamical
development of opinion in a small population of agents by means of a
computational model of opinion formation in a co-evolving network of socially
linked agents. The personal and external factors are taken into account by
assigning an individual attitude parameter to each agent, and by subjecting all
to an external but homogeneous field to simulate the effect of the media. We
then adjust the field strength in the model by using actual data on scientific
perception surveys carried out in two different populations, which allow us to
compare two different societies. We interpret the model findings with the aid
of simple mean field calculations. Our results suggest that scientifically
sound concepts are more difficult to acquire than concepts not validated by
science, since opposing individuals organize themselves in close communities
that prevent opinion consensus.Comment: 21 pages, 5 figures. Submitted to PLoS ON
Neutral theory of chemical reaction networks
To what extent do the characteristic features of a chemical reaction network
reflect its purpose and function? In general, one argues that correlations
between specific features and specific functions are key to understanding a
complex structure. However, specific features may sometimes be neutral and
uncorrelated with any system-specific purpose, function or causal chain. Such
neutral features are caused by chance and randomness. Here we compare two
classes of chemical networks: one that has been subjected to biological
evolution (the chemical reaction network of metabolism in living cells) and one
that has not (the atmospheric planetary chemical reaction networks). Their
degree distributions are shown to share the very same neutral
system-independent features. The shape of the broad distributions is to a large
extent controlled by a single parameter, the network size. From this
perspective, there is little difference between atmospheric and metabolic
networks; they are just different sizes of the same random assembling network.
In other words, the shape of the degree distribution is a neutral
characteristic feature and has no functional or evolutionary implications in
itself; it is not a matter of life and death.Comment: 13 pages, 8 figure
GREEN ACCOUNTING IN NORWEGIAN CONSTRUCTION
This master’s thesis aims to explore the application of Environmental Management
Accounting (EMA) in the Norwegian construction industry. EMA is an accounting
method that assists companies in identifying, measuring, and managing their
environmental impacts, costs, and benefits. With the introduction of the Corporate
Sustainable Reporting Directive (CSRD) in the EU, more actors in the industry will
be required to report in accordance with the European Sustainability Reporting
Standards (ESRS), which include Environmental, Social & Governance (ESG)
reporting requirements.
To achieve the objectives of the thesis, a qualitative multi-case study has been
conducted, involving five selected actors in the construction industry who will fall
under the scope of CSRD in 2024/25. The study maps out how these companies
use EMA for reporting purposes and how their control systems facilitate effective
reporting.
The findings reveal significant variation in the level of EMA use and associated tools
among the companies in the industry studied. Companies with a longer history of
sustainability reporting demonstrate greater sophistication in their use of EMA. These
companies possess more advanced tools and have automated reporting processes to
a greater extent. However, the implementation of EMA faces several challenges in
the industry, including the complexity of the CSRD, underdeveloped data collection
tools, and the management of substantial amounts of data.
The insights generated from this master’s thesis provide a systematic overview
of EMA practices in the Norwegian construction industry while also identifying
challenges that need to be addressed to achieve more efficient and comprehensive
reporting in line with CSRD and ESRS
Symmetry-allowed phase transitions realized by the two-dimensional fully frustrated XY class
A 2D Fully Frustrated XY(FFXY) class of models is shown to contain a new
groundstate in addition to the checkerboard groundstates of the standard 2D
FFXY model. The spin configuration of this additional groundstate is obtained.
Associated with this groundstate there are additional phase transitions. An
order parameter accounting for these new transitions is proposed. The
transitions associated with the new order parameter are suggested to be similar
to a 2D liquid-gas transition which implies Z_2-Ising like transitions. This
suggests that the class of 2D FFXY models belongs within a U(1) x Z_2 x
Z_2-designation of possible transitions, which implies that there are seven
different possible single and combined transitions. MC-simulations for the
generalized fully frustrated XY (GFFXY) model on a square lattice are used to
investigate which of these possibilities can be realized in practice: five of
the seven are encountered. Four critical points are deduced from the
MC-simulations, three consistent with central charge c=3/2 and one with c=1.
The implications for the standard 2D FFXY-model are discussed in particular
with respect to the long standing controversy concerning the characteristics of
its phase transitions.Comment: 8 pages, 8 figure
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