150 research outputs found
Tracking and supporting student learning in practical laboratory exercises spread over several days
Phase Transition in Two Species Zero-Range Process
We study a zero-range process with two species of interacting particles. We
show that the steady state assumes a simple factorised form, provided the
dynamics satisfy certain conditions, which we derive. The steady state exhibits
a new mechanism of condensation transition wherein one species induces the
condensation of the other. We study this mechanism for a specific choice of
dynamics.Comment: 8 pages, 3 figure
Tackling Salinity in Sustainable Agriculture—What Developing Countries May Learn from Approaches of the Developed World
Soil salinity is a common problem of the developing world as well as the developed world. However, the pace to reduce salinity is much slower in the developing world. The application of short-term approaches with an unsustainable supply of funds are the major reasons of low success. In contrast, the developed world has focused on long-term and sustainable techniques, and considerable funds per unit area have been allocated to reduce soil salinity. Here, we review the existing approaches in both worlds. Approaches like engineering and nutrient use were proven to be unsustainable, while limited breeding and biosaline approaches had little success in the developing countries. In contrast, advanced breeding and genetics tools were implemented in the developed countries to improve the salinity tolerance of different crops with more success. Resultantly, developed countries not only reduced the area for soil salinity at a higher rate, but more sustainable and cheaper ways to resolve the issue were implemented at the farmers’ field. Similarly, plant microbial approaches and the application of fertigation through drip irrigation have great potential for both worlds, and farmer participatory approaches are required to obtain fruitful outcomes. In this regard, a challenging issue is the transition of sustainable approaches from developed countries to developing ones, and possible methods for this are discussed
Conditional Distribution of Heavy Tailed Random Variables on Large Deviations of their Sum
It is known that large deviations of sums of subexponential random variables
are most likely realised by deviations of a single random variable. In this
article we give a detailed picture of how subexponential random variables are
distributed when a large deviation of their sum is observed.Comment: Results on local conditioning adde
Analytic study of clustering in shaken granular material using zero-range processes
We show that models used to described granular clustering due to vertical
shaking belong to the class of zero-range processes. This correspondence allows
us to derive exactly in a very easy and straightforward manner a number of
properties of the models like particle distribution functions, phase diagram,
and characteristic time of clusterization.Comment: 4 pages, 3 figures submitted to PR
Activities of leaf and spike carbohydrate-metabolic and antioxidant enzymes are linked with yield performance in three spring wheat genotypes grown under well-watered and drought conditions
Factorised steady states for multi-species mass transfer models
A general class of mass transport models with Q species of conserved mass is
considered. The models are defined on a lattice with parallel discrete time
update rules. For one-dimensional, totally asymmetric dynamics we derive
necessary and sufficient conditions on the mass transfer dynamics under which
the steady state factorises. We generalise the model to mass transfer on
arbitrary lattices and present sufficient conditions for factorisation. In both
cases, explicit results for random sequential update and continuous time limits
are given.Comment: 11 page
Condensation for a fixed number of independent random variables
A family of m independent identically distributed random variables indexed by
a chemical potential \phi\in[0,\gamma] represents piles of particles. As \phi
increases to \gamma, the mean number of particles per site converges to a
maximal density \rho_c<\infty. The distribution of particles conditioned on the
total number of particles equal to n does not depend on \phi (canonical
ensemble). For fixed m, as n goes to infinity the canonical ensemble measure
behave as follows: removing the site with the maximal number of particles, the
distribution of particles in the remaining sites converges to the grand
canonical measure with density \rho_c; the remaining particles concentrate
(condensate) on a single site.Comment: 6 page
Rigorous results on spontaneous symmetry breaking in a one-dimensional driven particle system
We study spontaneous symmetry breaking in a one-dimensional driven
two-species stochastic cellular automaton with parallel sublattice update and
open boundaries. The dynamics are symmetric with respect to interchange of
particles. Starting from an empty initial lattice, the system enters a symmetry
broken state after some time T_1 through an amplification loop of initial
fluctuations. It remains in the symmetry broken state for a time T_2 through a
traffic jam effect. Applying a simple martingale argument, we obtain rigorous
asymptotic estimates for the expected times ~ L ln(L) and ln() ~ L,
where L is the system size. The actual value of T_1 depends strongly on the
initial fluctuation in the amplification loop. Numerical simulations suggest
that T_2 is exponentially distributed with a mean that grows exponentially in
system size. For the phase transition line we argue and confirm by simulations
that the flipping time between sign changes of the difference of particle
numbers approaches an algebraic distribution as the system size tends to
infinity.Comment: 23 pages, 7 figure
UV-B Exposure of Black Carrot (<i>Daucus carota</i> ssp. <i>sativus</i> var. <i>atrorubens</i>) Plants Promotes Growth, Accumulation of Anthocyanin, and Phenolic Compounds
© The Author(s).Black carrot (Daucus carota L. ssp. sativus var. atroburens) is a root vegetable with anthocyanins as major phenolic compounds. The accumulation of phenolic compounds is a common response to UV-B exposure, acting as protective compounds and as antioxidants. In the present study, black carrot plants grown under a 12-h photoperiod were supplemented with UV-B radiation (21.6 kj m−2 day−1) during the last two weeks of growth. Carrot taproots and tops were harvested separately, and the effect of the UV-B irradiance was evaluated in terms of size (biomass and length), total monomeric anthocyanin content (TMC), total phenolic content (TPC), and phytohormones levels. The results showed that UV-B irradiance promoted plant growth, as shown by the elevated root (30%) and top (24%) biomass, the increased TMC and TPC in the root (over 10%), and the increased TPC of the top (9%). A hormone analysis revealed that, in response to UV-B irradiance, the levels of abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) decreased in tops while the level of the cytokinins cis-zeatin (cZ) and trans-zeatinriboside (tZR) increased in roots, which correlated with an amplified growth and the accumulation of anthocyanins and phenolic compounds. Beyond the practical implications that this work may have, it contributes to the understanding of UV-B responses in black carrotThis research was funded by the Danish Ministry of Science, Innovation, and Education grant number 6111-00240B and “Fundación Séneca” of the Agency of Science and Technology of the Region of Murcia grant number 20405/SF/17.Peer reviewe
- …