198 research outputs found
Flux-Bubble Models and Mesonic Molecules
It has been shown that the string-flip potential model reproduces most of the
bulk properties of nuclear matter, with the exception of nuclear binding.
Furthermore, it was postulated that this model, with the inclusion of the
colour-hyperfine interaction, should produce binding. In some recent work a
modified version of the string-flip potential model was developed, called the
flux-bubble model, which would allow for the addition of perturbative QCD
interactions. In attempts to construct a simple nucleon system using
the flux-bubble model (which only included colour-Coulomb interactions)
difficulties arose with trying to construct a many-body variational wave
function that would take into account the locality of the flux-bubble
interactions. In this talk we consider a toy system, a mesonic molecule in
order to understand these difficulties. En route, a new variational wave
function is proposed that may have a significant enough impact on the old
string-flip potential model results that the inclusion of perturbative effects
may not be needed.Comment: 8 pages, Latex, avec 9 eps files,
http://www.physics.carleton.ca/~boyce/papers/mrst97.p
Response of nitrogen fertilizer and legumes residues on biomass production and utilization in rice-legumes rotation
A cropping sequence including rice after winged bean, rice after bush bean, rice after corn, and rice after fallow with varying rates of nitrogen (N) fertilizer were carried out to investigate the effects of legume residues and N fertilizer to clarify dynamics of soil N supply, N utilization in soil-plant system and grain yield of rice. Nitrogen fertilizer was applied in both legumes at rates of 0, 2, 4 and 6 g m(-2). The first crop cycle for rice and corn were fertilized with N fertilizer at rates of 0, 4, 8 and 12 g m(-2) with no chemical fertilizer applied in the 2nd crop cycle for the legumes, corn and rice. In 2010, bush bean and winged bean accumulated 5.0-5.9 and 6.2-6.8 g N m(-2) of which 10.0-29.4 and 21.7-42.1 was derived from N-2 fixation. In 2011, bush bean and winged bean accumulated 4.7-5.6 and 5.8-6.9 g N m(-2) of which 13.2-28.8 and 29.5-41.4 was derived from N-2 fixation and estimated by total N difference method. Higher yield was recorded by rice after winged bean with N at rates of 4, 8 and 12 g N m(-2) during both years. This superior performance of rice after winged bean is likely linked to greater N fixation (21.7-42.1) and N uptake by both legumes. Such tropical legumes that improve productivity of rice might be attractive to farmers who are generally resource-poor farmers. The results revealed that bush bean and winged bean can supply >50 and >95 of N required for rice and can be a viable alternative organic N source to enhance soil fertility and reduce cost
Fruit Development, pigmentation and biochemical properties of wax apple as affected by localized application of GA(3) under field conditions
This study investigated the effects of gibberellin (GA(3)) on the fruit development, pigmentation and biochemical properties of wax apple. The wax apple trees were rubbing treated with 0, 20, 50 and 100 mgGA(3)/l under field conditions. The localized application (rubbing) of 50 mg GA(3)/l significantly increased the fruit set, fruit length and diameter, color development, weight and yield compared to the control. In addition, GA(3) treatments significantly reduced the fruit drop. With regard to the fruit quality, 50 mg/l GA(3) treatment increased the juice content, K+, TSS, total sugar and sugar acid ratio of wax apple fruits. In addition, higher vitamin C, phenol, flavonoid, anthocyanin, carotene content, PAL and antioxidant activities were recorded in the treated fruits. There was a positive correlation between the peel colour and TSS content and between the PAL activity and anthocyanin formation in the GA(3)-treated fruit. It was concluded that rubbing with 50 mg/L GA(3) at inflorescence developing point of phloem once a week from the tiny inflorescence bud until the flower opening resulted in better yield and quality of wax apple fruits and could be an effective technique to safe the environment from excessive spray
Why the uptake of eRehabilitation programs in stroke care is so difficulta focus group study in the Netherlands
Analysis and support of clinical decision makin
Investigating magmatic processes in the early Solar System using the Cl isotopic systematics of eucrites
Generally, terrestrial rocks, martian and chondritic meteorites exhibit a relatively narrow range in bulk and apatite Cl isotope compositions, with δ37Cl (per mil deviation from standard mean ocean chloride) values between − 5.6 and + 3.8 ‰. Lunar rocks, however, have more variable bulk and apatite δ37Cl values, ranging from ∼ − 4 to + 40 ‰. As the Howardite-Eucrite-Diogenite (HED) meteorites represent the largest suite of crustal and sub-crustal rocks available from a differentiated basaltic asteroid (4 Vesta), studying them for their volatiles may provide insights into planetary differentiation processes during the earliest Solar System history.
Here the abundance and isotopic composition of Cl in apatite were determined for seven eucrites representing a broad range of textural and petrological characteristics. Apatite Cl abundances range from ∼ 25 to 4900 ppm and the δ37Cl values range from − 3.98 to + 39.2 ‰. Samples with lower apatite H2O contents were typically also enriched in 37Cl but no systematic correlation between δ37Cl and δD values was observed across samples. Modelled Rayleigh fractionation and a strong positive correlation between bulk δ66Zn and apatite δ37Cl support the hypothesis that Cl degassed as metal chlorides from eucritic magmas, in a hydrogen-poor environment. In the case of lunar samples, it has been noted that δ37Cl values of apatite positively correlate with bulk La/Yb ratio. Interestingly, most eucrites show a negative correlation with bulk La/Yb ratio. Recently, isotopically light Cl values have been suggested to record the primary solar nebular signature. If this is the case then 4 Vesta, which accreted rapidly and early in Solar System history, could also record this primary nebular signature corresponding to the lightest Cl values measured here. The significant variation in Cl isotope composition observed within the eucrites are likely related to degassing of metal chlorides
Search for Supernova Neutrino-Bursts with the AMANDA Detector
The core collapse of a massive star in the Milky Way will produce a neutrino
burst, intense enough to be detected by existing underground detectors. The
AMANDA neutrino telescope located deep in the South Pole ice can detect MeV
neutrinos by a collective rate increase in all photo-multipliers on top of dark
noise. The main source of light comes from positrons produced in the
CC-reaction of anti-electron neutrinos on free protons \antinue + p \to e^+ +
n. This paper describes the first supernova search performed on the full sets
of data taken during 1997 and 1998 (215 days of live time) with 302 of the
detector's optical modules. No candidate events resulted from this search. The
performance of the detector is calculated, yielding a 70% coverage of the
Galaxy with one background fake per year with 90% efficiency for the detector
configuration under study. An upper limit at the 90% c.l. on the rate of
stellar collapses in the Milky Way is derived, yielding 4.3 events per year. A
trigger algorithm is presented and its performance estimated. Possible
improvements of the detector hardware are reviewed.Comment: 20 pages, 14 figures. Submitted to Astroparticle Physic
On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection
A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET
The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR
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