1,996,236 research outputs found
A Study of the Biology of \u3ci\u3eRhopalosiphum Padi\u3c/i\u3e (Homoptera: Aphididae) in Winter Wheat in Northwestern Indiana
Periodic collections of the bird cherry-oat aphid, Rhopalosiphum padi, during two years revealed small populations on winter wheat in Lafayette, Indiana. The greatest numbers were found on volunteer wheat plants before planting. In the autumn, aphids were detected on one-shoot plants by mid-October and also early March. The populations remained small until mid-June. We conclude that the aphid feeding did not significantly affect the plants, but helped spread barley yellow dwarf virus
Recommended from our members
Clarifying interoperability: The SISO CSPI PDG standard for commercial off-the-shelf simulation package interoperability reference models
Commercial-off-the-shelf simulation packages (CSPs), visual interactive modelling environments such as Arena, Anylogic, Flexsim, Simul8, Witness, etc., are important "black box" software tools that support the development, experimentation and visualization of simulation models. They are widely used in commerce, defence, health, manufacturing and logistics. There is a growing need to link together, or to interoperate, models developed in these CSPs across computer networks. The motivation for this includes data sensitivity, difficult to move resources and speed up
Low mass variable stars in the globular cluster NGC 6397
We have conducted a photometric survey of the globular cluster NGC 6397 in a
search for variable stars. We obtained ~11h of time-resolved photometric images
with one ne European Southern Observatory-Very Large Telescope using the FOcal
Reducer and low dispersion Spectrograph imager distributed over two consecutive
nights. We analyzed 8391 light curves of stars brighter than magnitude 23 with
the 465 nm-filter, and we identified 412 variable stars, reaching ~ 4.8 +- 0.2
per cent of variability with timescales between 0.004 and 2d, with amplitudes
variation greater than +- 0.2 mag.Comment: 9 figures, complementary dat
Low-frequency method for magnetothermopower and Nernst effect measurements on single crystal samples at low temperatures and high magnetic fields
We describe an AC method for the measurement of the longitudinal (Sxx) and
transverse (Sxy, i.e. Nernst) thermopower of mm-size single crystal samples at
low temperatures (T30 T). A low-frequency (33
mHz) heating method is used to increase the resolution, and to determine the
temperature gradient reliably in high magnetic fields. Samples are mounted
between two thermal blocks which are heated by a sinusoidal frequency f0 with a
p/2 phase difference. The phase difference between two heater currents gives a
temperature gradient at 2f0. The corresponding thermopower and Nernst effect
signals are extracted by using a digital signal processing method due. An
important component of the method involves a superconducting link, YBa2Cu3O7+d
(YBCO), which is mounted in parallel with sample to remove the background
magnetothermopower of the lead wires. The method is demonstrated for the quasi
two-dimensional organic conductor a-(BEDT-TTF)2KHg(SCN)4, which exhibits a
complex, magnetic field dependent ground state above 22.5 T at low
temperatures.Comment: 11 pages, 6 figures, 15 reference
Amplitude control of quantum interference
Usually, the oscillations of interference effects are controlled by relative
phases. We show that varying the amplitudes of quantum waves, for instance by
changing the reflectivity of beam splitters, can also lead to quantum
oscillations and even to Bell violations of local realism. We first study
theoretically a generalization of the Hong-Ou-Mandel experiment to arbitrary
source numbers and beam splitter transmittivity. We then consider a Bell type
experiment with two independent sources, and find strong violations of local
realism for arbitrarily large source number ; for small , one operator
measures essentially the relative phase of the sources and the other their
intensities. Since, experimentally, one can measure the parity of the number of
atoms in an optical lattice more easily than the number itself, we assume that
the detectors measure parity.Comment: 4 pages; 4 figure
Recommended from our members
COTS simulation package (CSP) interoperability - A solution to synchronous entity passing
In this paper we examine Commercial-Off-The- Shelf (COTS) Simulation Package (CSP) interoperability for one type of distributed simulation problem, namely synchronous entity passing. Synchronous entity passing is also referred to as the bounded buffer interoperability reference model. It deals with the case where for entities passed between models the receiving queue is bounded or the receiving workstation has limited capacity. This means the sending model must check the status of the receiving model before it can send entities. Correspondingly, the receiving model should update the status information dynamically when it changes. Similar to the work done on asynchronous entity passing, the High Level Architecture is chosen as the underlying standard to support reuse and interoperability. To simplify the integration of the CSP and the HLA, a middleware layer called DSManager is provided. Some new problems generated for synchronous entity passing are discussed and solutions are proposed together with a description of their implementation. Two sets of experiments are conducted to evaluate the solutions using a CSP Emulator (CSPE) which supports both standalone and distributed simulation
Options for the SELEX state D_{s\J}^+(2632)
We consider possible assignments for the D_{s\J}^+(2632), which was
recently reported in D and DK final states by the SELEX
Collaboration at Fermilab. The most plausible quark model assignment for this
state is the first radial excitation () of the
D, although the predicted mass and strong decay branching fractions
for this assignment are not in agreement with the SELEX data. The reported
dominance of D over DK appears especially problematic. An intriguing
similarity to the K is noted. --^3\D_1 configuration
mixing is also considered, and we find that this effect is unlikely to resolve
the branching fraction discrepancy. Other interpretations as a -hybrid
or a two-meson molecule are also considered, but appear unlikely. Thus, if this
state is confirmed, it will require reconsideration of the systematics of
charmed meson spectroscopy and strong decays.Comment: 6 revtex4 pages, 2 eps figure
- …