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Amino acids composition and oxygen isotopes in the Shisr 033 CR chondrite
Finite resolution measurement of the non-classical polarization statistics of entangled photon pairs
By limiting the resolution of quantum measurements, the measurement induced
changes of the quantum state can be reduced, permitting subsequent measurements
of variables that do not commute with the initially measured property. It is
then possible to experimentally determine correlations between non-commuting
variables. The application of this method to the polarization statistics of
entangled photon pairs reveals that negative conditional probabilities between
non-orthogonal polarization components are responsible for the violation of
Bell's inequalities. Such negative probabilities can also be observed in finite
resolution measurements of the polarization of a single photon. The violation
of Bell's inequalities therefore originates from local properties of the
quantum statistics of single photon polarization.Comment: 15 pages, 5 figures and 1 table, new figure to illustrate results,
improved explanation of statistical analysi
Responses to water stress extremes in diverse red clover germplasm accessions
Red clover (Trifolium pratense L.), a key perennial pastoral species used globally, can strengthen pastural mixes to withstand increasingly disruptive weather patterns from climate change. Breeding selections can be refined for this purpose by obtaining an in-depth understanding of key functional traits. A replicated randomized complete block glasshouse pot trial was used to observe trait responses critical to plant performance under control (15% VMC), water deficit (5% VMC) and waterlogged conditions (50% VMC) in seven red clover populations and compared against white clover. Twelve morphological and physiological traits were identified as key contributors to the different plant coping mechanisms displayed. Under water deficit, the levels of all aboveground morphological traits decreased, highlighted by a 41% decrease in total dry matter and 50% decreases in both leaf number and leaf thickness compared to the control treatment. An increase in root to shoot ratio indicated a shift to prioritizing root maintenance by sacrificing shoot growth, a trait attributed to plant water deficit tolerance. Under waterlogging, a reduction in photosynthetic activity among red clover populations reduced several morphological traits including a 30% decrease in root dry mass and total dry matter, and a 34% decrease in leaf number. The importance of root morphology for waterlogging was highlighted with low performance of red clover: there was an 83% decrease in root dry mass compared to white clover which was able to maintain root dry mass and therefore plant performance. This study highlights the importance of germplasm evaluation across water stress extremes to identify traits for future breeding programs
Worldlines on Orbifolds and the Fayet-Iliopoulos Term
We adapt ``string-inspired'' worldline techniques to one-loop calculations on
orbifolds, in particular on the orbifold. Our method also allows for
the treatment of brane-localized terms, or bulk-brane couplings. For
demonstration, we reproduce the well-known result for the one-loop induced
Fayet-Iliopoulos term in rigidly supersymmetric Abelian gauge theory, and
generalize it to the case where soft supersymmetry breaking mass terms for the
bulk scalar fields are present on the branes.Comment: Typos corrected, clarifying remarks adde
VHE Gamma-ray Afterglow Emission from Nearby GRBs
Gamma-ray Bursts (GRBs) are among the potential extragalactic sources of
very-high-energy (VHE) gamma-rays. We discuss the prospects of detecting VHE
gamma-rays with current ground-based Cherenkov instruments during the afterglow
phase. Using the fireball model, we calculate the synchrotron self-Compton
(SSC) emission from forward-shock electrons. The modeled results are compared
with the observational afterglow data taken with and/or the sensitivity level
of ground-based VHE instruments (e.g. STACEE, H.E.S.S., MAGIC, VERITAS, and
Whipple). We find that modeled SSC emission from bright and nearby bursts such
as GRB 030329 are detectable by these instruments even with a delayed
observation time of ~10 hours.Comment: Proceeding of "Heidelberg International Symposium on High Energy
Gamma-Ray Astronomy", held in Heidelberg, 7-11 July 2008, submitted to AIP
Conference Proceedings. 4 pages, 3 figures, 1 tabl
Quantum enhancement of N-photon phase sensitivity by interferometric addition of down-converted photon pairs to weak coherent light
It is shown that the addition of down-converted photon pairs to coherent
laser light enhances the N-photon phase sensitivity due to the quantum
interference between components of the same total photon number. Since most of
the photons originate from the coherent laser light, this method of obtaining
non-classical N-photon states is much more efficient than methods based
entirely on parametrically down-converted photons. Specifically, it is possible
to achieve an optimal phase sensitivity of about delta phi^2=1/N^(3/2), equal
to the geometric mean of the standard quantum limit and the Heisenberg limit,
when the average number of down-converted photons contributing to the N-photon
state approaches (N/2)^(1/2).Comment: 21 pages, including 6 figures. Extended version gives more details on
down-conversion efficiencies and clarifies the relation between phase
sensitivity and squeezing. The title has been changed in order to avoid
misunderstandings regarding these concept
Using 222 Rn for hydrograph separationin a micro basin (Luxembourg)
In order to obtain information on the hydrological signature of rivers during and after heavy rain events, small
catchment areas are selected as experimental sites. Hydrograph separations based on environmental tracers are
performed. Natural isotopic tracers such as 18O, 2H and particularly 222Rn may help to distinguish the components
dominating the outflow, particularly of 'pre-event waters', 'event waters' and 'post-event waters'. Even with
moderate concentrations in groundwater, radon can be a very sensitive indicator of groundwater input into rivers.
The selected microbasin under investigation is situated in the western part of Luxembourg and belongs to the Attert
River catchment. At chosen points at the basin's outflow radon detectors continuously measure radon activity
in water. The radon monitors are installed together with high precision thermometers, conductivity meters,
flow meters and automatic water samplers for chemical analysis. Besides the continuous measurements, grab
water samples are taken at different locations along the stream, most of them during periods of heavy rain events.
Presented are the results of a one year measurement campaign. During the dry season i.e. during more or less
continuous discharge conditions, the observed mean values do not show substantial variations and can be used
as reference values. Fluctuations of the measured data during rain events are discussed and the interplay between
the different parameters analysed
Numerical Study of Excited States in the Shastry-Sutherland Model
We investigate excited states of the Shastry-Sutherland model using a kind of
variational method. Starting from various trial states which include one or two
triplet dimers, we numerically pursue the best evaluation of the energy for
each set of quantum numbers. We present the energy difference as a function of
either the coupling ratio or the momentum and compare them with the
perturbative calculations. Our data suggest that the helical order phase exists
between the singlet dimer phase and the magnetically ordered phase. In
comparison with the experimental data we can estimate the intra-dimer coupling
J and the inter-dimer coupling J' for
SrCu2(BO3)2 : J'/J =0.65 and J = 87K.Comment: 15pages, 5figures to be published in JPS
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