993 research outputs found
Differential approach for the study of duals of algebraic-geometric codes on surfaces
The purpose of the present article is the study of duals of functional codes
on algebraic surfaces. We give a direct geometrical description of them, using
differentials. Even if this geometrical description is less trivial, it can be
regarded as a natural extension to surfaces of the result asserting that the
dual of a functional code on a curve is a differential code. We study the
parameters of such codes and state a lower bound for their minimum distance.
Using this bound, one can study some examples of codes on surfaces, and in
particular surfaces with Picard number 1 like elliptic quadrics or some
particular cubic surfaces. The parameters of some of the studied codes reach
those of the best known codes up to now.Comment: 21 page
A note on the minimum distance of quantum LDPC codes
We provide a new lower bound on the minimum distance of a family of quantum
LDPC codes based on Cayley graphs proposed by MacKay, Mitchison and
Shokrollahi. Our bound is exponential, improving on the quadratic bound of
Couvreur, Delfosse and Z\'emor. This result is obtained by examining a family
of subsets of the hypercube which locally satisfy some parity conditions
Plant water uptake modelling : added value of cross-disciplinary approaches
Abstract In recent years, research interest in plant water uptake strategies has significantly grown in many disciplines such as hydrology, plant ecology and ecophysiology. Quantitative modelling approaches to estimate plant water uptake and the spatio-temporal dynamics significantly advanced from different disciplines across scales. Despite this progress, major limitations, i.e. to predict plant water uptake under drought or it?s impact at large-scales remain. These are less attributed to limitations in process understanding, but rather to a lack of implementation of cross-disciplinary insights in plant water uptake model structure. The main goal of this review is to highlight how the 4 dominant model approaches, e.g. Feddes approach, hydrodynamic approach, optimality and statistical approaches, can be and have been used to create interdisciplinary hybrid models enabeling a holistic system understanding that e.g. embeds plant water uptake plasticity into a broader conceptual view of soil-plant feedbacks of water, nutrient and carbon cycling or reflects observed drought responses of plant-soil feedbacks and their dynamics under e.g. drought. Specifically, we provide examples of how integration of Bayesian and hydrodynamic approaches might overcome challenges in interpreting plant water uptake related to e.g. different travel and residence times of different plant water sources or trade-offs between root system optimization to forage for water and nutrients during different seasons and phenological stages.In recent years, research interest in plant water uptake strategies has rapidly increased in many disciplines, such as hydrology, plant ecology and ecophysiology. Quantitative modelling approaches to estimate plant water uptake and spatiotemporal dynamics have significantly advanced through different disciplines across scales. Despite this progress, major limitations, for example, predicting plant water uptake under drought or drought impact at large scales, remain. These are less attributed to limitations in process understanding, but rather to a lack of implementation of cross-disciplinary insights into plant water uptake model structure. The main goal of this review is to highlight how the four dominant model approaches, that is, Feddes approach, hydrodynamic approach, optimality and statistical approaches, can be and have been used to create interdisciplinary hybrid models enabling a holistic system understanding that, among other things, embeds plant water uptake plasticity into a broader conceptual view of soil-plant feedbacks of water, nutrient and carbon cycling, or reflects observed drought responses of plant-soil feedbacks and their dynamics under, that is, drought. Specifically, we provide examples of how integration of Bayesian and hydrodynamic approaches might overcome challenges in interpreting plant water uptake related to different travel and residence times of different plant water sources or trade-offs between root system optimization to forage for water and nutrients during different seasons and phenological stages.Peer reviewe
Thermal annealing study of swift heavy-ion irradiated zirconia
Sintered samples of monoclinic zirconia (alpha-ZrO2) have been irradiated at
room temperature with 6.0-GeV Pb ions in the electronic slowing down regime.
X-ray diffraction (XRD) and micro-Raman spectroscopy measurements showed
unambiguously that a transition to the 'metastable' tetragonal phase
(beta-ZrO2) occurred at a fluence of 6.5x10^12 cm-2 for a large electronic
stopping power value (approx 32.5 MeV m-1). At a lower fluence of
1.0x10^12 cm-2, no such phase transformation was detected. The
back-transformation from beta- to alpha-ZrO2 induced by isothermal or
isochronal thermal annealing was followed by XRD analysis. The
back-transformation started at an onset temperature around 500 K and was
completed by 973 K. Plots of the residual tetragonal phase fraction deduced
from XRD measurements versus annealing temperature or time are analyzed with
first- or second-order kinetic models. An activation energy close to 1 eV for
the back-transformation process is derived either from isothermal annealing
curves, using the so-called "cross-cut" method, or from the isochronal
annealing curve, using a second-order kinetic law. Correlation with the thermal
recovery of ion-induced paramagnetic centers monitored by EPR spectroscopy is
discussed. Effects of crystallite size evolution and oxygen migration upon
annealing are also addressed
The signature of 44Ti in Cassiopeia A revealed by IBIS/ISGRI on INTEGRAL
We report the detection of both the 67.9 and 78.4 keV 44Sc gamma-ray lines in
Cassiopeia A with the INTEGRAL IBIS/ISGRI instrument. Besides the robustness
provided by spectro-imaging observations, the main improvements compared to
previous measurements are a clear separation of the two 44Sc lines together
with an improved significance of the detection of the hard X-ray continuum up
to 100 keV. These allow us to refine the determination of the 44Ti yield and to
constrain the nature of the nonthermal continuum emission. By combining
COMPTEL, BeppoSAX/PDS and ISGRI measurements, we find a line flux of (2.5 +/-
0.3)*10(-5) cm(-2) s(-1) leading to a synthesized 44Ti mass of 1.6
(+0.6-0.3)*10(-4) solar mass. This high value suggests that Cas A is peculiar
in comparison to other young supernova remnants, from which so far no line
emission from 44Ti decay has been unambiguously detected.Comment: 5 pages, 4 figures, Accepted for publication in ApJ
Hierarchical Set Decision Diagrams and Regular Models
This paper presents algorithms and data structures that exploit a compositional and hierarchical specification to enable more efficient symbolic model-checking. We encode the state space and transition relation using hierarchical Set Decision Diagrams (SDD) [9]. In SDD, arcs of the structure are labeled with sets, themselves stored as SDD.
To exploit the hierarchy of SDD, a structured model representation is needed. We thus introduce a formalism integrating a simple notion of type and instance. Complex composite behaviors are obtained using a synchronization mechanism borrowed from process calculi. Using this relatively general framework, we investigate how to capture similarities in regular and concurrent models. Experimental results are presented, showing that this approach can outperform in time and memory previous work in this area
Infection levels and species diversity of ascaridoid nematodes in Atlantic cod, Gadus morhua, are correlated with geographic area and fish size
Atlantic cod (Gadus morhua) is among the most important commercial fish species on the world market. Its
infection by ascaridoid nematodes has long been known, Pseudoterranova even being named cod worm. In the
present study, 755 individuals were sampled in the Barents, Baltic and North Seas during 2012–2014.
Prevalences for Anisakis in whole fish and in fillets in the different fishing areas varied from 16 to 100% and
from 12 to 90% respectively. Abundance was also greatly influenced by the sampling area. Generalized additive
model results indicate higher numbers of Anisakis in the North Sea, even after the larger body size was accounted
for. Numbers and prevalence of Anisakis were positively related to fish length or weight. The prevalence of
parasites in whole fish and in fillets was also influenced by the season, with the spring displaying a peak for the
prevalence in whole fish and, at the same time, a drop for the prevalence in fillets. Whereas 46% of cod had
Anisakis larvae in their fillets, the majority (39%) had parasites mainly in the ventral part of the fillet and only
12% had parasites in their dorsal part. This observation is of importance for the processing of the fish. Indeed,
the trimming of the ventral part of the cod fillet would allow the almost total elimination of ascaridoids except
for cod from the Baltic Sea where there was no difference between the dorsal and the ventral part.
The presence of other ascaridoid genera was also noticeable in some areas. For Pseudoterranova, the highest
prevalence (45%) in whole fish was observed in the Northern North Sea, whereas the other areas had prevalences between 3 and 16%. Contracaecum was present in every commercial size cod sampled in the Baltic Sea
with an intensity of up to 96 worms but no Contracaecum was isolated from the Central North Sea. Non-zoonotic
Hysterothylacium was absent from the Baltic Sea but with a prevalence of 83% in the Barents and the Northern
North Sea.
A subsample of worms was identified with genetic-molecular tools and assigned to the species A. simplex (s.s.),
A. pegreffii, P. decipiens (s.s.), P. krabbei, C. osculatum and H. aduncum. In addition to high prevalence and
abundance values, the cod sampled in this study presented a diversity of ascaridoid nematodes with a majority of
fish displaying a co-infection. Out of 295 whole infected fish, 269 were co-infected by at least 2 genera
On finitely ambiguous B\"uchi automata
Unambiguous B\"uchi automata, i.e. B\"uchi automata allowing only one
accepting run per word, are a useful restriction of B\"uchi automata that is
well-suited for probabilistic model-checking. In this paper we propose a more
permissive variant, namely finitely ambiguous B\"uchi automata, a
generalisation where each word has at most accepting runs, for some fixed
. We adapt existing notions and results concerning finite and bounded
ambiguity of finite automata to the setting of -languages and present a
translation from arbitrary nondeterministic B\"uchi automata with states to
finitely ambiguous automata with at most states and at most accepting
runs per word
Integrative taxonomy and molecular phylogeny of the plant-parasitic nematode genus Paratylenchus (nematoda: paratylenchinae) : linking species with molecular barcodes
Pin nematodes of the genus Paratylenchus are obligate ectoparasites of a wide variety of plants that are distributed worldwide. In this study, individual morphologically vouchered nematode specimens of fourteen Paratylenchus species, including P. aculentus, P. elachistus, P. goodeyi, P. holdemani, P. idalimus, P. microdorus, P. nanus, P. neoamblycephalus, P. straeleni and P. veruculatus, are unequivocally linked to the D2-D3 of 28S, ITS, 18S rRNA and COI gene sequences. Combined with scanning electron microscopy and a molecular analysis of an additional nine known and thirteen unknown species originating from diverse geographic regions, a total of 92 D2-D3 of 28S, 41 ITS, 57 18S rRNA and 111 COI new gene sequences are presented. Paratylenchus elachistus, P. holdemani and P. neoamblycephalus are recorded for the first time in Belgium and P. idalimus for the first time in Europe. Paratylenchus is an excellent example of an incredibly diverse yet morphologically minimalistic plant-parasitic genus, and this study provides an integrated analysis of all available data, including coalescence-based molecular species delimitation, resulting in an updated Paratylenchus phylogeny and the corrective reassignment of 18 D2-D3 of 28S, 3 ITS, 3 18S rRNA and 25 COI gene sequences that were previously unidentified or incorrectly classified
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