3,262 research outputs found
Predicting Stellar Angular Diameters from , , , Photometry
Determining the physical properties of microlensing events depends on having
accurate angular sizes of the source star. Using long-baseline optical
interferometry we are able to measure the angular sizes of nearby stars with
uncertainties . We present empirically derived relations of angular
diameters that are calibrated using both a sample of dwarfs/subgiants and a
sample of giant stars. These relations are functions of five color indices in
the visible and near-infrared, and have uncertainties of 1.8-6.5% depending on
the color used. We find that a combined sample of both main-sequence and
evolved stars of A-K spectral types is well fit by a single relation for each
color considered. We find that in the colors considered, metallicity does not
play a statistically significant role in predicting stellar size, leading to a
means of predicting observed sizes of stars from color alone.Comment: 8 pages, 1 figure, accepted for publication in MNRA
Accurate multi-boson long-time dynamics in triple-well periodic traps
To solve the many-boson Schr\"odinger equation we utilize the
Multiconfigurational time-dependent Hartree method for bosons (MCTDHB). To be
able to attack larger systems and/or to propagate the solution for longer
times, we implement a parallel version of the MCTDHB method thereby realizing
the recently proposed [Streltsov {\it et al.} arXiv:0910.2577v1] novel idea how
to construct efficiently the result of the action of the Hamiltonian on a
bosonic state vector. We study the real-space dynamics of repulsive bosonic
systems made of N=12, 51 and 3003 bosons in triple-well periodic potentials.
The ground state of this system is three-fold fragmented. By suddenly strongly
distorting the trap potential, the system performs complex many-body quantum
dynamics. At long times it reveals a tendency to an oscillatory behavior around
a threefold fragmented state. These oscillations are strongly suppressed and
damped by quantum depletions. In spite of the richness of the observed
dynamics, the three time-adaptive orbitals of MCTDHB(M=3) are capable to
describe the many-boson quantum dynamics of the system for short and
intermediate times. For longer times, however, more self-consistent
time-adaptive orbitals are needed to correctly describe the non-equilibrium
many-body physics. The convergence of the MCTDHB() method with the number
of self-consistent time-dependent orbitals used is demonstrated.Comment: 37 pages, 7 figure
Empirical study of cartograms
We report on an empirical study investigating the effectiveness and efficiency of spatial inference making with contiguous (value-by-area) cartograms, compared to informational equivalent choropleth maps, combined with graduated circles. We find significant differences in people's inference-making performance dependent on the map type. Overall, results suggest that the choropleth map with graduated circles is more effective and more efficient than the cartogram for the analysis of population census data. However, map effectiveness and efficiency also significantly depends on the inference task complexity, and more surprisingly, on the shape characteristics of the depicted enumeration units. For simple tasks, cartograms seem as effective and efficient as the more traditional mapping method. For complex inference questions, inference performance with cartograms is significantly dependent on whether regular or irregular zones are distorted. As we know still very little about the perception and cognition of cartograms, we hope to shed new light for this intriguing mapping method with this empirical study
Uji Viabilitas Benih Ketimun (Cucumis Sativus L) Hasil Perlakuan Penyerbukan Berbagai Serangga
The aim of the study was to test the cucumber seeds viability which was pollinated by different pollinators. Good seed viability is important to ensure the production. In fact successful of pollination will influence seed quality and production. This study was conducted in a completely randomized design (CRD) with one factor. Seeds used in this study were collected from previous experiment which was pollinated by different pollinators (insects, wind and human). We germinated 20 seeds per treatment. The result showed insects pollinated seeds are better than wind and human influenced. The density of the insects are not influenced the viability of the seeds. Germination rate, germination time, uniformity of seedlings is better in insect's pollinated seeds
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