47 research outputs found
Recommended from our members
Summary of the laser working group
The laser working group considered several options to deliver synchronized laser pulses of the required energy to the photocathode and laser triggered switches. These requirements actually decreased during the course of the workshop, and the values finally settled upon (<10 {mu}J in 100 fs at {approximately}250 nm for the photocathode and {approximately}20 mJ in 2 ps near either 250 nm or 1 {mu}m for the switches) were considered to be well within the state of the art. Some development work may be required, however, to provide a system that has the desirable characteristics of stability, ease of use and low maintenance. The baseline concept, which is similar to a number of existing systems, utilizes doubled Nd:YAG-pumped dye oscillator/amplifiers to produce an upconverted picosecond pulse that can be amplified to tens of mJ in a KrF excimer laser. A fraction of the dye oscillator output is also compressed by means of a fiber-grating compressor and further amplified in a dye amplifier before being upconverted to produce the synchronized pulse for the photocathode. 9 refs., 1 fig
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Acúmulo de nitrogênio, fósforo e potássio pelo algodoeiro sob irrigação cultivado em sistemas convencional e adensado
The contributions of nitrogen-fixing crop legumes to the productivity of agricultural systems
Abstract
Data collated from around the world indicate that, for every tonne of shoot dry matter produced by crop legumes, the
symbiotic relationship with rhizobia is responsible for fixing, on average on a whole plant basis (shoots and nodulated
roots), the equivalent of 30-40 kg of nitrogen (N). Consequently, factors that directly influence legume growth (e.g. water
and nutrient availability, disease incidence and pests) tend to be the main determinants of the amounts of N2 fixed.
However, practices that either limit the presence of effective rhizobia in the soil (no inoculation, poor inoculant quality),
increase soil concentrations of nitrate (excessive tillage, extended fallows, fertilizer N), or enhance competition for soil
mineralN (intercropping legumes with cereals) can also be critical. Much of the N2 fixed by the legume is usually removed
at harvest in high-protein seed so that the net residual contributions of fixed N to agricultural soils after the harvest of
legume grain may be relatively small. Nonetheless, the inclusion of legumes in a cropping sequence generally improves the
productivity of following crops. Whilesome of these rotational effects may be associated with improvements in availability
ofN in soils, factors unrelated to N also play an important role. Recent results suggest that one such non-N benefit may be
due to the impact on soil biology of hydrogen emitted from nodules as a by-product of'N, fixation
Effect of Straw Application on Rice Yields and Nutrient Availability on an Alkaline and a pH-neutral Soil in a Sahelian Irrigation Scheme
Bisphenol A Induces a Distinct Transcriptome Profile in the Male Fish of the Marine Medaka Oryzias javanicus
Search for the rare decays and
We present results from a search for the flavor-changing neutral current decays and , where is either an or pair. The data sample comprises decays collected with the BABAR detector at the PEP-II Factory. We obtain the 90% C.L. upper limits and , close to Standard Model predictions for these branching fractions. We have also obtained limits on the lepton-family-violating decays and