2,912 research outputs found
Evaluation of the users value of salts against apple scab and powdery mildew for fruit production
The research was aimed at finding anti resistance strategies for Integrated fruit growing.
As the salts tested may be approvable for organic farming, the trial results are also of
value for the development of scab an mildew control strategies for organic fruit growing. As
new fungicides are mainly unisite action fungicides, the problem of fungicide resistance
development is becoming more important every year. Combining chemical fungicides,
which is the best anti-resistance strategy, is not always possible or recommended in the
case when the number of available chemical fungicides are limited or a reduction in
fungicide use is asked for. Therefore the use of salts as an anti-resistance strategy was
looked upon. The salts evaluated were K(HCO3), KH2PO3, KHPO4 and K2SiO3. When
using these salts as an anti-resistance strategy the efficacy obtained when spraying the
compounds alone was often to low to be used in rotation with chemical fungicides. Only
with K(HCO3)2 a good efficacy can be observed in some years. The variation in efficacy
with K(HCO3)2 observed is higher for powdery mildew. K(HCO3)2 can be considered as a
ideal product for scab control in organic orchards at moments of low infection risk
Probing the quantumness of channels with mixed states
We present an alternative approach to the derivation of benchmarks for
quantum channels, such as memory or teleportation channels. Using the concept
of effective entanglement and the verification thereof, a testing procedure is
derived which demands very few experimental resources. The procedure is
generalized by allowing for mixed test states. By constructing optimized
measure & re-prepare channels, the benchmarks are found to be very tight in the
considered experimental regimes.Comment: 11 Pages, 9 Figures, published versio
A Correlation between the Emission Intensity of Self-Assembled Germanium Islands and the Quality Factor of Silicon Photonic Crystal Nanocavities
We present a comparative micro-photoluminescence study of the emission
intensity of self-assembled germanium islands coupled to the resonator mode of
two-dimensional silicon photonic crystal defect nanocavities. The emission
intensity is investigated for cavity modes of L3 and Hexapole cavities with
different cavity quality factors. For each of these cavities many nominally
identical samples are probed to obtain reliable statistics. As the quality
factor increases we observe a clear decrease in the average mode emission
intensity recorded under comparable optical pumping conditions. This clear
experimentally observed trend is compared with simulations based on a
dissipative master equation approach that describes a cavity weakly coupled to
an ensemble of emitters. We obtain evidence that reabsorption of photons
emitted into the cavity mode is responsible for the observed trend. In
combination with the observation of cavity linewidth broadening in power
dependent measurements, we conclude that free carrier absorption is the
limiting effect for the cavity mediated light enhancement under conditions of
strong pumping.Comment: 8 pages, 5 figure
Feature-based interference from unattended visual field during attentional tracking in younger and older adults
The ability to attend to multiple objects that move in the visual field is
important for many aspects of daily functioning. The attentional capacity for
such dynamic tracking, however, is highly limited and undergoes age-related
decline. Several aspects of the tracking process can influence performance.
Here, we investigated effects of feature-based interference from distractor
objects that appear in unattended regions of the visual field with a
hemifield-tracking task. Younger and older participants performed an
attentional tracking task in one hemifield while distractor objects were
concurrently presented in the unattended hemifield. Feature similarity between
objects in the attended and unattended hemifields as well as motion speed and
the number of to-be-tracked objects were parametrically manipulated. The
results show that increasing feature overlap leads to greater interference
from the unattended visual field. This effect of feature-based interference
was only present in the slow speed condition, indicating that the interference
is mainly modulated by perceptual demands. High-performing older adults showed
a similar interference effect as younger adults, whereas low-performing adults
showed poor tracking performance overall
The role of relatives in decisions concerning life-prolonging treatment in patients with end-stage malignant disorders: informants, advocates or surrogate decision-makers?
Background: This study examines the extent to which relatives of severely ill cancer patients are involved in the decision to limit treatment (DLT), their role in communicating patient wishes and the incidence of and reasons for disagreement with relatives. Patients and methods: This cohort study followed 70 patients with terminal cancer, for whom a limitation of life-prolonging treatment was being considered. ‘Embedded researchers' recorded patients' wishes and the relatives' roles and disagreements with DLT. Results: Although 63 out of 70 patients had relatives present during their care, only 32% of relatives were involved in DLT. Physicians were more likely to know the end-of-life (EOL) preferences for those patients who had visiting relatives than those without them (78% versus 29%, P = 0.014). Most relatives supported patients in voicing their preferences (68%), but one-third acted against the known or presumed wishes of patients (32%). Disagreements with patients' relatives occurred in 21% of cases, and predominantly when relatives held views that contradicted known patient preferences (71% versus 7%, P = 0.001). Conclusion: If relatives are to play an important part in EOL decision making, we must devise strategies to recognise their potential as patients' advocates as well as their own need
Modified spin-wave theory with ordering vector optimization I: frustrated bosons on the spatially anisotropic triangular lattice
We investigate a system of frustrated hardcore bosons, modeled by an XY
antiferromagnet on the spatially anisotropic triangular lattice, using
Takahashi's modified spin-wave (MSW) theory. In particular we implement
ordering vector optimization on the ordered reference state of MSW theory,
which leads to significant improvement of the theory and accounts for quantum
corrections to the classically ordered state. The MSW results at zero
temperature compare favorably to exact diagonalization (ED) and projected
entangled-pair state (PEPS) calculations. The resulting zero-temperature phase
diagram includes a 1D quasi-ordered phase, a 2D Neel ordered phase, and a 2D
spiraling ordered phase. We have strong indications that the various ordered or
quasi-ordered phases are separated by spin-liquid phases with short-range
correlations, in analogy to what has been predicted for the Heisenberg model on
the same lattice. Within MSW theory we also explore the finite-temperature
phase diagram. We find that the zero-temperature long-range-ordered phases turn
into quasi-ordered phases (up to a Berezinskii-Kosterlitz-Thouless
temperature), while zero-temperature quasi-ordered phases become short-range
correlated at finite temperature. These results show that modified spin-wave
theory is very well suited for describing ordered and quasi-ordered phases of
frustrated XY spins (or, equivalently, of frustrated lattice bosons) both at
zero and finite temperatures. While MSW theory, just as other theoretical
methods, cannot describe spin-liquid phases, its breakdown provides a fast
method for singling out Hamiltonians which may feature these intriguing quantum
phases. We thus suggest a tool for guiding our search for interesting systems
whose properties are necessarily studied with a physical quantum simulator.Comment: 40 pages, 16 figure
Recommended from our members
Editorial : Sea Ice: Bridging Spatial-Temporal Scales and Disciplines
Non peer reviewe
Increased Belief Instability in Psychotic Disorders Predicts Treatment Response to Metacognitive Training
BACKGROUND AND HYPOTHESIS: In a complex world, gathering information and adjusting our beliefs about the world is of paramount importance. The literature suggests that patients with psychotic disorders display a tendency to draw early conclusions based on limited evidence, referred to as the jumping-to-conclusions bias, but few studies have examined the computational mechanisms underlying this and related belief-updating biases. Here, we employ a computational approach to understand the relationship between jumping-to-conclusions, psychotic disorders, and delusions. STUDY DESIGN: We modeled probabilistic reasoning of 261 patients with psychotic disorders and 56 healthy controls during an information sampling task-the fish task-with the Hierarchical Gaussian Filter. Subsequently, we examined the clinical utility of this computational approach by testing whether computational parameters, obtained from fitting the model to each individual's behavior, could predict treatment response to Metacognitive Training using machine learning. STUDY RESULTS: We observed differences in probabilistic reasoning between patients with psychotic disorders and healthy controls, participants with and without jumping-to-conclusions bias, but not between patients with low and high current delusions. The computational analysis suggested that belief instability was increased in patients with psychotic disorders. Jumping-to-conclusions was associated with both increased belief instability and greater prior uncertainty. Lastly, belief instability predicted treatment response to Metacognitive Training at the individual level. CONCLUSIONS: Our results point towards increased belief instability as a key computational mechanism underlying probabilistic reasoning in psychotic disorders. We provide a proof-of-concept that this computational approach may be useful to help identify suitable treatments for individual patients with psychotic disorders
- …