124 research outputs found
In vitro response of promising tomato genotypes for tolerance to osmotic stress
Drought is a major abiotic factor that limits plant growth and productivity. Tomato is an important vegetable crop and area under production is limited by irrigation water scarcity. Four cultivars of tomato were grown as callus cultures under conditions of water stress, which was induced by addition of polyethylene glycol (6000) in the medium. The presence of PEG in the medium decreased relative growth rate and increased dry matter content in all treatments compared with the control. In all cultivars, proline levels increased in response to water stress. Also, there was decreased shoot induction in all cultivars with increase PEG treatments. The number of shoot forming in PS-10 and Peto was higher then Roma and Nora cultivars. This result can be used for in vitro screening and manipulations of tomato cultivars for improvement of drought tolerance
Extreme Value Statistics of Eigenvalues of Gaussian Random Matrices
We compute exact asymptotic results for the probability of the occurrence of
large deviations of the largest (smallest) eigenvalue of random matrices
belonging to the Gaussian orthogonal, unitary and symplectic ensembles. In
particular, we show that the probability that all the eigenvalues of an (NxN)
random matrix are positive (negative) decreases for large N as ~\exp[-\beta
\theta(0) N^2] where the Dyson index \beta characterizes the ensemble and the
exponent \theta(0)=(\ln 3)/4=0.274653... is universal. We compute the
probability that the eigenvalues lie in the interval [\zeta_1,\zeta_2] which
allows us to calculate the joint probability distribution of the minimum and
the maximum eigenvalue. As a byproduct, we also obtain exactly the average
density of states in Gaussian ensembles whose eigenvalues are restricted to lie
in the interval [\zeta_1,\zeta_2], thus generalizing the celebrated Wigner
semi-circle law to these restricted ensembles. It is found that the density of
states generically exhibits an inverse square-root singularity at the location
of the barriers. These results are confirmed by numerical simulations.Comment: 17 pages Revtex, 5 .eps figures include
The Statistics of the Number of Minima in a Random Energy Landscape
We consider random energy landscapes constructed from d-dimensional lattices
or trees. The distribution of the number of local minima in such landscapes
follows a large deviation principle and we derive the associated law exactly
for dimension 1. Also of interest is the probability of the maximum possible
number of minima; this probability scales exponentially with the number of
sites. We calculate analytically the corresponding exponent for the Cayley tree
and the two-leg ladder; for 2 to 5 dimensional hypercubic lattices, we compute
the exponent numerically and compare to the Cayley tree case.Comment: 18 pages, 8 figures, added background on landscapes and reference
Wearable Devices in Health Monitoring from the Environmental towards Multiple Domains: A Survey
The World Health Organization (WHO) recognizes the environmental, behavioral, physiological, and psychological domains that impact adversely human health, well-being, and quality of life (QoL) in general. The environmental domain has significant interaction with the others. With respect to proactive and personalized medicine and the Internet of medical things (IoMT), wearables are most important for continuous health monitoring. In this work, we analyze wearables in healthcare from a perspective of innovation by categorizing them according to the four domains. Furthermore, we consider the mode of wearability, costs, and prolonged monitoring. We identify features and investigate the wearable devices in the terms of sampling rate, resolution, data usage (propagation), and data transmission. We also investigate applications of wearable devices. Web of Science, Scopus, PubMed, IEEE Xplore, and ACM Library delivered wearables that we require to monitor at least one environmental parameter, e.g., a pollutant. According to the number of domains, from which the wearables record data, we identify groups: G1, environmental parameters only; G2, environmental and behavioral parameters; G3, environmental, behavioral, and physiological parameters; and G4 parameters from all domains. In total, we included 53 devices of which 35, 9, 9, and 0 belong to G1, G2, G3, and G4, respectively. Furthermore, 32, 11, 7, and 5 wearables are applied in general health and well-being monitoring, specific diagnostics, disease management, and non-medical. We further propose customized and quantified output for future wearables from both, the perspectives of users, as well as physicians. Our study shows a shift of wearable devices towards disease management and particular applications. It also indicates the significant role of wearables in proactive healthcare, having capability of creating big data and linking to external healthcare systems for real-time monitoring and care delivery at the point of perception
Gravitational lensing in the Kerr-Randers optical geometry
A new geometric method to determine the deflection of light in the equatorial
plane of the Kerr solution is presented, whose optical geometry is a surface
with a Finsler metric of Randers type. Applying the Gauss-Bonnet theorem to a
suitable osculating Riemannian manifold, adapted from a construction by Naz\i
m, it is shown explicitly how the two leading terms of the asymptotic
deflection angle of gravitational lensing can be found in this way.Comment: 7 pages, 1 figure. Accepted by Gen. Rel. Grav. Version 2: change of
notation in sec.
Parameterized Inapproximability of Target Set Selection and Generalizations
In this paper, we consider the Target Set Selection problem: given a graph
and a threshold value for any vertex of the graph, find a minimum
size vertex-subset to "activate" s.t. all the vertices of the graph are
activated at the end of the propagation process. A vertex is activated
during the propagation process if at least of its neighbors are
activated. This problem models several practical issues like faults in
distributed networks or word-to-mouth recommendations in social networks. We
show that for any functions and this problem cannot be approximated
within a factor of in time, unless FPT = W[P],
even for restricted thresholds (namely constant and majority thresholds). We
also study the cardinality constraint maximization and minimization versions of
the problem for which we prove similar hardness results
Exploring a string-like landscape
We explore inflationary trajectories within randomly-generated
two-dimensional potentials, considered as a toy model of the string landscape.
Both the background and perturbation equations are solved numerically, the
latter using the two-field formalism of Peterson and Tegmark which fully
incorporates the effect of isocurvature perturbations. Sufficient inflation is
a rare event, occurring for only roughly one in potentials. For models
generating sufficient inflation, we find that the majority of runs satisfy
current constraints from WMAP. The scalar spectral index is less than 1 in all
runs. The tensor-to-scalar ratio is below the current limit, while typically
large enough to be detected by next-generation CMB experiments and perhaps also
by Planck. In many cases the inflationary consistency equation is broken by the
effect of isocurvature modes.Comment: 24 pages with 8 figures incorporated, matches version accepted by
JCA
A Stringy Mechanism for A Small Cosmological Constant
Based on the probability distributions of products of random variables, we
propose a simple stringy mechanism that prefers the meta-stable vacua with a
small cosmological constant. We state some relevant properties of the
probability distributions of functions of random variables. We then illustrate
the mechanism within the flux compactification models in Type IIB string
theory. As a result of the stringy dynamics, we argue that the generic
probability distribution for the meta-stable vacua typically peaks with a
divergent behavior at the zero value of the cosmological constant. However, its
suppression in the single modulus model studied here is modest.Comment: 36 pages, 8 figure
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