441 research outputs found
Tension, rigidity and preferential curvature of interfaces between coexisting polymer solutions
The properties of the interface in a phase-separated solution of polymers
with different degrees of polymerization and Kuhn segment lengths are
calculated. The starting point is the planar interface, the profile of which is
calculated in the so-called 'blob model', which incorporates the solvent in an
implicit way. The next step is the study of a metastable droplet phase formed
by imposing a chemical potential different from that at coexistence. The
pressure difference across the curved interface, which corresponds to this
higher chemical potential, is used to calculate the curvature properties of the
droplet. Interfacial tensions, Tolman lengths and rigidities are calculated and
used for predictions for a realistic experimental case. The results suggest
that interfaces between phase-separated solutions of polymers exhibit, in
general, a preferential curvature, which stabilizes droplets of low molecular
mass polymer in a high molecular mass macroscopic phase.Comment: 21 pages; 8 figures; accepted for publication in Macromolecule
HENNOVATION: Learnings from Promoting Practice-Led Multi-Actor Innovation Networks to Address Complex Animal Welfare Challenges within the Laying Hen Industry
The Hennovation project, an EU H2020 funded thematic network, aimed to explore the potential value of practice-led multi-actor innovation networks within the laying hen industry. The project proposed that husbandry solutions can be practice-led and effectively supported to achieve durable gains in sustainability and animal welfare. It encouraged a move away from the traditional model of science providing solutions for practice, towards a collaborative approach where expertise from science and practice were equally valued. During the 32-month project, the team facilitated 19 multi-actor networks in five countries through six critical steps in the innovation process: problem identification, generation of ideas, planning, small scale trials, implementation and sharing with others. The networks included farmers, processors, veterinarians, technical advisors, market representatives and scientists. The interaction between the farmers and the other network actors, including scientists, was essential for farmer innovation. New relationships emerged between the scientists and farmers, based on experimental learning and the co-production of knowledge for improving laying hen welfare. The project demonstrated that a practice-led approach can be a major stimulus for innovation with several networks generating novel ideas and testing them in their commercial context. The Hennovation innovation networks not only contributed to bridging the science-practice gap by application of existing scientific solutions in practice but more so by jointly finding new solutions. Successful multi-actor, practice-led innovation networks appeared to depend upon the following key factors: active participation from relevant actors, professional facilitation, moderate resource support and access to relevant expertise. Farmers and processors involved in the project were often very enthusiastic about the approach, committing significant time to the network’s activities. It is suggested that the agricultural research community and funding agencies should place greater value on practice-led multi-actor innovation networks alongside technology and advisor focused initiatives to improve animal welfare and embed best practices
Comparative interactomics analysis of different ALS-associated proteins identifies converging molecular pathways
Amyotrophic lateral sclerosis (ALS) is a devastating
neurological disease with no effective treatment
available. An increasing number of genetic causes of ALS
are being identified, but how these genetic defects lead to
motor neuron degeneration and to which extent they affect
common cellular pathways remains incompletely understood.
To address these questions, we performed an interactomic
analysis to identify binding partners of wild-type
(WT) and ALS-associated mutant versions of ATXN2,
C9orf72, FUS, OPTN, TDP-43 and UBQLN2 in neuronal
cells. This analysis identified several known but also many
novel binding partners of these proteins
De status van het menselijk embryo
VakpublicatieFaculteit der Wijsbegeert
Good Random Matrices over Finite Fields
The random matrix uniformly distributed over the set of all m-by-n matrices
over a finite field plays an important role in many branches of information
theory. In this paper a generalization of this random matrix, called k-good
random matrices, is studied. It is shown that a k-good random m-by-n matrix
with a distribution of minimum support size is uniformly distributed over a
maximum-rank-distance (MRD) code of minimum rank distance min{m,n}-k+1, and
vice versa. Further examples of k-good random matrices are derived from
homogeneous weights on matrix modules. Several applications of k-good random
matrices are given, establishing links with some well-known combinatorial
problems. Finally, the related combinatorial concept of a k-dense set of m-by-n
matrices is studied, identifying such sets as blocking sets with respect to
(m-k)-dimensional flats in a certain m-by-n matrix geometry and determining
their minimum size in special cases.Comment: 25 pages, publishe
Single Molecule Statistics and the Polynucleotide Unzipping Transition
We present an extensive theoretical investigation of the mechanical unzipping
of double-stranded DNA under the influence of an applied force. In the limit of
long polymers, there is a thermodynamic unzipping transition at a critical
force value of order 10 pN, with different critical behavior for homopolymers
and for random heteropolymers. We extend results on the disorder-averaged
behavior of DNA's with random sequences to the more experimentally accessible
problem of unzipping a single DNA molecule. As the applied force approaches the
critical value, the double-stranded DNA unravels in a series of discrete,
sequence-dependent steps that allow it to reach successively deeper energy
minima. Plots of extension versus force thus take the striking form of a series
of plateaus separated by sharp jumps. Similar qualitative features should
reappear in micromanipulation experiments on proteins and on folded RNA
molecules. Despite their unusual form, the extension versus force curves for
single molecules still reveal remnants of the disorder-averaged critical
behavior. Above the transition, the dynamics of the unzipping fork is related
to that of a particle diffusing in a random force field; anomalous,
disorder-dominated behavior is expected until the applied force exceeds the
critical value for unzipping by roughly 5 pN.Comment: 40 pages, 18 figure
Surface induced disorder in body-centered cubic alloys
We present Monte Carlo simulations of surface induced disordering in a model
of a binary alloy on a bcc lattice which undergoes a first order bulk
transition from the ordered DO3 phase to the disordered A2 phase. The data are
analyzed in terms of an effective interface Hamiltonian for a system with
several order parameters in the framework of the linear renormalization
approach due to Brezin, Halperin and Leibler. We show that the model provides a
good description of the system in the vicinity of the interface. In particular,
we recover the logarithmic divergence of the thickness of the disordered layer
as the bulk transition is approached, we calculate the critical behavior of the
maxima of the layer susceptibilities, and demonstrate that it is in reasonable
agreement with the simulation data. Directly at the (110) surface, the theory
predicts that all order parameters vanish continuously at the surface with a
nonuniversal, but common critical exponent. However, we find different
exponents for the order parameter of the DO3 phase and the order parameter of
the B2 phase. Using the effective interface model, we derive the finite size
scaling function for the surface order parameter and show that the theory
accounts well for the finite size behavior of the DO3 ordering but not for that
of B2 ordering. The situation is even more complicated in the neighborhood of
the (100) surface, due to the presence of an ordering field which couples to
the B2 order.Comment: To appear in Physical Review
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