12,691 research outputs found
Seed conservation in ex situ genebanks - genetic studies on longevity in barley
Recognizing the danger due to a permanent risk of loss of the genetic variability of cultivated plants and their wild relatives in response to changing environmental conditions and cultural practices, plant ex situ genebank collections were created since the beginning of the last century. World-wide more than 6 million accessions have been accumulated of which more than 90% are stored as seeds. Research on seed longevity was performed in barley maintained for up to 34 years in the seed store of the German ex situ genebank of the Leibniz-Institute of Plant Genetics and Crop Plant Research in Gatersleben. A high intraspecific variation was detected in those natural aged accessions. In addition three doubled haploid barley mapping populations being artificial aged were investigated to study the inheritance of seed longevity. Quantitative trait locus (QTL) mapping was based on a transcript map. Major QTLs were identified on chromosomes 2H, 5H (two) and 7H explaining a phenotypic variation of up to 54%. A sequence homology search was performed to derive the putative function of the genes linked to the QTLs
How ripples turn into dots: modeling ion-beam erosion under oblique incidence
Pattern formation on semiconductor surfaces induced by low energetic ion-beam
erosion under normal and oblique incidence is theoretically investigated using
a continuum model in form of a stochastic, nonlocal, anisotropic
Kuramoto-Sivashinsky equation. Depending on the size of the parameters this
model exhibits hexagonally ordered dot, ripple, less regular and even rather
smooth patterns. We investigate the transitional behavior between such states
and suggest how transitions can be experimentally detected.Comment: 11 pages, 4 figures, submitted for publication, revised versio
Influence of Different Cutting Frequencies and Fertilization on Grass Silage Quality
The influence of different cutting frequencies and fertilization on dry matter yield, botanical composition, nutrient concentration and fermentation quality of grass silage was investigated. Altogether four treatments were compared; two 5-cut-treatnents with two different fertilizer levels, one 3-cut-treatment with fertilizer and one 2-cuttreatment without fertilizer. In the 5-cut-treatments the double fertilizer amount produced a 10% higher dry matter yield and also a higher proportion of grasses. The fermentation quality of these silages was mostly good, especially in autumn when the high nitrate content improved the quality. The 3- cut and 2-cut-variants showed a higher grass proportion, a higher crude fibre and lower crude protein and sugar contents. The quality of these silages was poor due to increases in butyric acid content. The conclusion of this study is that intensively produced fodder is easier to ensile than extensively produced fodder
Moments of nonclassicality quasiprobabilities
A method is introduced for the verification of nonclassicality in terms of
moments of nonclassicality quasiprobability distributions. The latter are
easily obtained from experimental data and will be denoted as nonclassicality
moments. Their relation to normally-ordered moments is derived, which enables
us to verify nonclassicality by using well established criteria. Alternatively,
nonclassicality criteria are directly formulated in terms of nonclassicality
moments. The latter converge in proper limits to the usually used criteria, as
is illustrated for squeezing and sub-Poissonian photon statistics. Our theory
also yields expectation values of any observable in terms of nonclassicality
moments.Comment: 6 pages, 3 figure
Waveguide QED: Many-Body Bound State Effects on Coherent and Fock State Scattering from a Two-Level System
Strong coupling between a two-level system (TLS) and bosonic modes produces
dramatic quantum optics effects. We consider a one-dimensional continuum of
bosons coupled to a single localized TLS, a system which may be realized in a
variety of plasmonic, photonic, or electronic contexts. We present the exact
many-body scattering eigenstate obtained by imposing open boundary conditions.
Multi-photon bound states appear in the scattering of two or more photons due
to the coupling between the photons and the TLS. Such bound states are shown to
have a large effect on scattering of both Fock and coherent state wavepackets,
especially in the intermediate coupling strength regime. We compare the
statistics of the transmitted light with a coherent state having the same mean
photon number: as the interaction strength increases, the one-photon
probability is suppressed rapidly, and the two- and three-photon probabilities
are greatly enhanced due to the many-body bound states. This results in
non-Poissonian light.Comment: 10 page
On a theory of neutrino oscillations with entanglement
We show that, despite appearances, a theoretical approach to neutrino
oscillation in which the neutrino and its interaction partners are entangled
yields the standard result for the neutrino oscillation wavelength. We also
shed some light on the question of why plane-wave approaches to the neutrino
oscillation problem can yield the correct oscillation wavelength even though
they do not explicitly account for the localization of the neutrino source and
the detector.Comment: RevTeX 4, 12 pages, 1 figure; v2: Minor clarifications, references
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Multipartite minimum uncertainty products
In our previous work we have found a lower bound for the multipartite
uncertainty product of the position and momentum observables over all separable
states. In this work we are trying to minimize this uncertainty product over a
broader class of states to find the fundamental limits imposed by nature on the
observable quantites. We show that it is necessary to consider pure states only
and find the infimum of the uncertainty product over a special class of pure
states (states with spherically symmetric wave functions). It is shown that
this infimum is not attained. We also explicitly construct a parametrized
family of states that approaches the infimum by varying the parameter. Since
the constructed states beat the lower bound for separable states, they are
entangled. We thus show that there is a gap that separates the values of a
simple measurable quantity for separable states from entangled ones and we also
try to find the size of this gap.Comment: 18 pages, 5 figure
Cashing In or Paying Out? Analysis of the Relation Between Corporate Earnings and Cash
This paper examines the relation between corporate earnings and cash in the US on annual basis in the period 2002 to 2022. We document that both earnings and cash holdings are non-stationary and therefore we use the Granger representation theorem and the methods of cointegration analysis and make an attempt to model the relation between these company variables. We document a negative sign of the cointegration coefficient estimate that is statistically significant. The statistical significance confirms that cash and earnings are cointegrated, and depend on each other. However, the significance of the models with earnings as the dependent variable is larger, and the coefficient estimates are more reliably negative. These results indicate that earnings depend on cash to a larger degree than cash depends on earnings
Strongly correlated photons generated by coupling a three- or four-level system to a waveguide
We study the generation of strongly correlated photons by coupling an atom to
photonic quantum fields in a one-dimensional waveguide. Specifically, we
consider a three-level or four-level system for the atom. Photon-photon bound
states emerge as a manifestation of the strong photon-photon correlation
mediated by the atom. Effective repulsive or attractive interaction between
photons can be produced, causing either suppressed multiphoton transmission
(photon blockade) or enhanced multiphoton transmission (photon-induced
tunneling). As a result, nonclassical light sources can be generated on demand
by sending coherent states into the proposed system. We calculate the
second-order correlation function of the transmitted field and observe bunching
and antibunching caused by the bound states. Furthermore, we demonstrate that
the proposed system can produce photon pairs with a high degree of spectral
entanglement, which have a large capacity for carrying information and are
important for large-alphabet quantum communication.Comment: 13+ pages, 7 figure
Dynamical control of two-level system's decay and long time freezing
We investigate with exact numerical calculation coherent control of a
two-level quantum system's decay by subjecting the two-level system to many
periodic ideal phase modulation pulses. For three spectrum intensities
(Gaussian, Lorentzian, and exponential), we find both suppression and
acceleration of the decay of the two-level system, depending on difference
between the spectrum peak position and the eigen frequency of the two-level
system. Most interestingly, the decay of the two-level system freezes after
many control pulses if the pulse delay is short. The decay freezing value is
half of the decay in the first pulse delay.Comment: 6 pages, 6 figures, published in Phys. Rev.
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