1,304 research outputs found
Oxygen-limited thermal tolerance is seen in a plastron-breathing insect and can be induced in a bimodal gas exchanger.
Thermal tolerance has been hypothesized to result from a mismatch between oxygen supply and demand. However, the generality of this hypothesis has been challenged by studies on various animal groups, including air-breathing adult insects. Recently, comparisons across taxa have suggested that differences in gas exchange mechanisms could reconcile the discrepancies found in previous studies. Here, we test this suggestion by comparing the behaviour of related insect taxa with different gas exchange mechanisms, with and without access to air. We demonstrate oxygen-limited thermal tolerance in air-breathing adults of the plastron-exchanging water bug Aphelocheirus aestivalis. Ilyocoris cimicoides, a related, bimodal gas exchanger, did not exhibit such oxygen-limited thermal tolerance and relied increasingly on aerial gas exchange with warming. Intriguingly, however, when denied access to air, oxygen-limited thermal tolerance could also be induced in this species. Patterns in oxygen-limited thermal tolerance were found to be consistent across life-history stages in these insects, with nymphs employing the same gas exchange mechanisms as adults. These results advance our understanding of oxygen limitation at high temperatures; differences in the degree of respiratory control appear to modulate the importance of oxygen in setting tolerance limits
Etnocentrisme in Suriname
Contains fulltext :
3324.pdf (publisher's version ) (Open Access
Een methodologische vergelijking: De Likert-, en de semantische differentiaal meettechniek toegepast op etnocentrische attitudes
Contains fulltext :
3311.pdf (publisher's version ) (Open Access
Stabilization of Capacitated Matching Games
An edge-weighted, vertex-capacitated graph G is called stable if the value of
a maximum-weight capacity-matching equals the value of a maximum-weight
fractional capacity-matching. Stable graphs play a key role in characterizing
the existence of stable solutions for popular combinatorial games that involve
the structure of matchings in graphs, such as network bargaining games and
cooperative matching games.
The vertex-stabilizer problem asks to compute a minimum number of players to
block (i.e., vertices of G to remove) in order to ensure stability for such
games. The problem has been shown to be solvable in polynomial-time, for
unit-capacity graphs. This stays true also if we impose the restriction that
the set of players to block must not intersect with a given specified maximum
matching of G.
In this work, we investigate these algorithmic problems in the more general
setting of arbitrary capacities. We show that the vertex-stabilizer problem
with the additional restriction of avoiding a given maximum matching remains
polynomial-time solvable. Differently, without this restriction, the
vertex-stabilizer problem becomes NP-hard and even hard to approximate, in
contrast to the unit-capacity case.
Finally, in unit-capacity graphs there is an equivalence between the
stability of a graph, existence of a stable solution for network bargaining
games, and existence of a stable solution for cooperative matching games. We
show that this equivalence does not extend to the capacitated case.Comment: 14 pages, 3 figure
CdSe/CdS dot-in-rods nanocrystals fast blinking dynamics
The blinking dynamics of colloidal core-shell CdSe/CdS dot-in-rods is studied
in detail at the single particle level. Analyzing the autocorrelation function
of the fluorescence intensity, we demonstrate that these nanoemitters are
characterized by a short value of the mean duration of bright periods (ten to a
few hundreds of microseconds). The comparison of the results obtained for
samples with different geometries shows that not only the shell thickness is
crucial but also the shape of the dot- in-rods. Increasing the shell aspect
ratio results in shorter bright periods suggesting that surface traps impact
the stability of the fluorescence intensity
Non-Markovian non-stationary completely positive open quantum system dynamics
By modeling the interaction of a system with an environment through a renewal
approach, we demonstrate that completely positive non-Markovian dynamics may
develop some unexplored non-standard statistical properties. The renewal
approach is defined by a set of disruptive events, consisting in the action of
a completely positive superoperator over the system density matrix. The random
time intervals between events are described by an arbitrary waiting-time
distribution. We show that, in contrast to the Markovian case, if one performs
a system-preparation (measurement) at an arbitrary time, the subsequent
evolution of the density matrix evolution is modified. The non-stationary
character refers to the absence of an asymptotic master equation even when the
preparation is performed at arbitrary long times. In spite of this property, we
demonstrate that operator expectation values and operators correlations have
the same dynamical structure, establishing the validity of a non-stationary
quantum regression hypothesis. The non-stationary property of the dynamic is
also analyzed through the response of the system to an external weak
perturbation.Comment: 13 pages, 3 figure
Simple model for the power-law blinking of single semiconductor nanocrystals
We assign the blinking of nanocrystals to electron tunneling towards a uniform spatial distribution of traps. This naturally explains the power-law distribution of off times, and the power-law correlation function we measured on uncapped CdS dots. Capped dots, on the other hand, present extended on times leading to a radically different correlation function. This is readily described in our model by involving two different, dark and bright, charged states. Coulomb blockade prevents further ionization of the charged dot, thus giving rise to long, power-law distributed off and on times
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