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Aufsatz
Electronic origin of bond softening and hardening in femtosecond-laser-excited magnesium
(IOP, 2014)
Many ultrafast structural phenomena in solids at high fluences are related to the hardening or softening of particular lattice vibrations at lower fluences. In this paper we relate femtosecond-laser-induced phonon frequency changes to changes in the electronic density of states, which need to be evaluated only in the electronic ground state, following phonon displacement patterns. We illustrate this relationship for a particular lattice vibration of magnesium, for which we—surprisingly—find that there is both softening ...
Aufsatz
Controlling the transport of an ion: classical and quantum mechanical solutions
(IOP, 2014)
The accurate transport of an ion over macroscopic distances represents a challenging control problem due to the different length and time scales that enter and the experimental limitations on the controls that need to be accounted for. Here, we investigate the performance of different control techniques for ion transport in state-of-the-art segmented miniaturized ion traps. We employ numerical optimization of classical trajectories and quantum wavepacket propagation as well as analytical solutions derived from invariant ...
Aufsatz
Happy growers! Relationship quality in the German organic apple chain
(IFAMA, 2014)
Relational factors between supply chain actors have been acknowledged to contribute significantly to competitiveness. With the example of the German market for organic apples the suitability of the concept of the Relational View for explaining competitiveness was investigated. Structured interviews were conducted with selected actors of the supply chain. Actors at all levels of the supply chain proved to be highly committed and described their business relations as satisfying and trustful. Strong vertical and horizontal ...
Aufsatz
Effect of Auger recombination and leakage on the droop in InGaN/GaN quantum well LEDs
(Optical Society of America, 2014)
We investigate the effect of the epitaxial structure and the acceptor doping profile on the efficiency droop in InGaN/GaN LEDs by the physics based simulation of experimental internal quantum efficiency (IQE) characteristics. The device geometry is an integral part of our simulation approach. We demonstrate that even for single quantum well LEDs the droop depends critically on the acceptor doping profile. The Auger recombination was found to increase stronger than with the third power of the carrier density and has ...
Aufsatz
Signaling of Pigment-Dispersing Factor (PDF) in the Madeira Cockroach Rhyparobia maderae
(2014)
The insect neuropeptide pigment-dispersing factor (PDF) is a functional ortholog of vasoactive intestinal polypeptide, the coupling factor of the mammalian circadian pacemaker. Despite of PDF's importance for synchronized circadian locomotor activity rhythms its signaling is not well understood. We studied PDF signaling in primary cell cultures of the accessory medulla, the circadian pacemaker of the Madeira cockroach. In Ca2+ imaging studies four types of PDF-responses were distinguished. In regularly bursting type ...
Aufsatz
Left preference for sport tasks does not necessarily indicate left-handedness
(2014)
In the elite domain of interactive sports, athletes who demonstrate a left preference (e.g., holding a weapon with the left hand in fencing or boxing in a ‘southpaw’ stance) seem overrepresented. Such excess indicates a performance advantage and was also interpreted as evidence in favour of frequency-dependent selection mechanisms to explain the maintenance of left-handedness in humans. To test for an overrepresentation, the incidence of athletes’ lateral preferences is typically compared with an expected ratio of ...
Aufsatz
Optimal control theory for a unitary operation under dissipative evolution
(2014)
We show that optimizing a quantum gate for an open quantum system requires
the time evolution of only three states irrespective of the dimension of Hilbert
space. This represents a significant reduction in computational resources compared
to the complete basis of Liouville space that is commonly believed
necessary for this task. The reduction is based on two observations: the target is
not a general dynamical map but a unitary operation; and the time evolution of
two properly chosen states is sufficient to ...
Aufsatz
Loss of wobble uridine modification in tRNA anticodons interferes with TOR pathway signaling
(2014)
Previous work in yeast has suggested that modification of tRNAs,
in particular uridine bases in the anticodon wobble position (U34), is linked to
TOR (target of rapamycin) signaling. Hence, U34 modification mutants were
found to be hypersensitive to TOR inhibition by rapamycin. To study whether
this involves inappropriate TOR signaling, we examined interaction between
mutations in TOR pathway genes (tip41Δ, sap190Δ, ppm1Δ, rrd1Δ) and U34
modification defects (elp3Δ, kti12Δ, urm1Δ, ncs2Δ) and found the ...
Aufsatz
Effects of changing water availability on land use in irrigated mountain oases of Al Jabal Al Akhdar, northern Oman
(2014)
In Oman, during the last three decades, agricultural water use and groundwater extraction has dramatically increased
to meet the needs of a rapidly growing population and major changes in lifestyle. This has triggered agricultural
land-use changes which have been poorly investigated. In view of this our study aimed at analysing patterns of shortterm
land-use changes (2007-2009) in the five irrigated mountain oases of Ash Sharayjah, Al’Ayn, Al’Aqr, Qasha’ and
Masayrat ar Ruwajah situated in the northern Oman Hajar ...
Aufsatz
Detecting ultrafast interatomic electronic processes in media by fluorescence
(In: New journal of physics. - London : IOP, 2014, 16, 102002, 1-9, 2014)
Interatomic coulombic decay (ICD), a radiationless transition in weakly bonded systems, such as solutes or van der Waals bound aggregates, is an effective source for electrons of low kinetic energy. So far, the ICD processes could only be probed in ultra-high vacuum by using electron and/or ion spectroscopy. Here we show that resonant ICD processes can also be detected by measuring the subsequently emitted characteristic fluorescence radiation, which makes their study in dense media possible.