570 research outputs found
Effect of sewage sludge on the incidence of corn stalk rot caused by Fusarium.
During the last decades, sewage started to be treated in order to reduce the pollution of rivers, resulting in the production of a sludge rich in organic matter and nutrients, called sewage sludge. Among the alternatives for final discarding, the agricultural use is one of the most convenient, because it combines disposal and recycling. However, using sewage sludge as a fertilizer causes alterations in the physical, chemical and biological properties of the soils. The soilborne plant pathogens are highly influenced by the way the soil is managed; thus, sewage sludge may interfere with the occurrence of diseases caused by these microorganisms. The objective of this study was to evaluate the effect of sewage sludge on corn stalk rot, caused by Fusarium spp
Efeito da incorporação de lodo de esgoto sobre a fusariose do milho.
O trabalho objetivou verificar os fatores quĂmicos e microbiolĂłgicos do lodo de esgoto e do solo responsĂĄveis pela incidĂȘncia da podridĂŁo do colmo do milho, causada por Fusarium em solo fertilizado com lodo, e foi desenvolvido em condiçÔes de campo, numa ĂĄrea que vem sendo tratada com lodo e cultivada com milho desde 1999 em latossolo vermelho distrofĂ©rrico (textura argilosa), localizada no municĂpio de JaguariĂșna/SP. Os dois lodos utilizados oram obtidos nas EstaçÔes de Tratamento de Esgoto de Franca e de Barueri/SP. Os lodos foram incorporados ao solo nas concentraçÔes de 0, 1, 2, 4 e 8 vezes a dose recomendada com base no teor de nitrogĂȘnio, em dois cultivos sucessivos de milho(Savana 133S) nas safras 2001/2002 e 2002/2003, em parcelas de 200 m2. As doses de lodo foram comparadas com a adubação mineral recomendada para a cultura do milho. Os tratamentos foram distribuĂdos em delineamento experimental casualizado em blocos e com trĂȘs repetiçÔes. Foram verificadas, nas safras de 2001/2002/ 2 2002/2003, diferenças significativas entre as doses de lodo de esgoto, sobre a variação de Fusarium spp. no solo, na rizosfera, na raiz, no colmo e na semente, bem como sobre a incidĂȘncia de plantas com podridĂŁo no colmo e nas espigas. As anĂĄlises de regressĂŁo mostraram que a porcentagem de plantas doentes oi positivamente correlacionada com a concentração dos lodos incorporados ao solo. Os coeficientes de determinação para o cultivo de 2001/2002 foram de R2=0,61 e R2=0,32, enquanto para o cultivo de 2002/2003 foram de R2=0,76 e R2=0,45, para os lodos de Franca e Barueri, respectivamente. As concentraçÔes de lodos tambĂ©m apresentaram correlação positiva com a comunidade de Fusarium do solo e da rizosfera e com a incidĂȘncia de Fusarium na raiz, no colmo e na semente. As correlaçÔes entre a comunidade de Fusarium do solo e da rizosfera e o percentual de plantas doentes com os atributos quĂmicos do solo foram significativas e positivas, para os dois tipos de lodos ao nĂvel de 1 e 5%, para o teor de fĂłsforo, cĂĄlcio, condutividade elĂ©trica, CTC, N-amĂŽnio e N-nitrato, nos dois anos de cultivo.Tese (Doutorado em Agronomia) - Faculdade de CiĂȘncias AgronĂŽmicas, Universidade Estadual Paulista JĂșlio de Mesquita Filho, Botucatu. Orientador: Raquel Ghini (CNPMA)
Asymptotic statistics of the n-sided planar Poisson-Voronoi cell. I. Exact results
We achieve a detailed understanding of the -sided planar Poisson-Voronoi
cell in the limit of large . Let be the probability for a cell to
have sides. We construct the asymptotic expansion of up to
terms that vanish as . We obtain the statistics of the lengths of
the perimeter segments and of the angles between adjoining segments: to leading
order as , and after appropriate scaling, these become independent
random variables whose laws we determine; and to next order in they have
nontrivial long range correlations whose expressions we provide. The -sided
cell tends towards a circle of radius (n/4\pi\lambda)^{\half}, where
is the cell density; hence Lewis' law for the average area of
the -sided cell behaves as with . For
the cell perimeter, expressed as a function of the polar
angle , satisfies , where is known Gaussian
noise; we deduce from it the probability law for the perimeter's long
wavelength deviations from circularity. Many other quantities related to the
asymptotic cell shape become accessible to calculation.Comment: 54 pages, 3 figure
Dimensional crossover of a boson gas in multilayers
We obtain the thermodynamic properties for a non-interacting Bose gas
constrained on multilayers modeled by a periodic Kronig-Penney delta potential
in one direction and allowed to be free in the other two directions. We report
Bose-Einstein condensation (BEC) critical temperatures, chemical potential,
internal energy, specific heat, and entropy for different values of a
dimensionless impenetrability between layers. The BEC critical
temperature coincides with the ideal gas BEC critical temperature
when and rapidly goes to zero as increases to infinity for
any finite interlayer separation. The specific heat \textit{vs} for
finite and plane separation exhibits one minimum and one or two maxima
in addition to the BEC, for temperatures larger than which highlights
the effects due to particle confinement. Then we discuss a distinctive
dimensional crossover of the system through the specific heat behavior driven
by the magnitude of . For the crossover is revealed by the change
in the slope of and when , it is evidenced by a broad
minimum in .Comment: Ten pages, nine figure
Solving the inhomogeneous Bethe-Salpeter equation
We develop an advanced method of solving homogeneous and inhomogeneous
Bethe-Salpeter equations by using the expansion over the complete set of
4-dimensional spherical harmonics. We solve Bethe-Salpeter equations for bound
and scattering states of scalar and spinor particles for the case of one meson
exchange kernels. Phase shifts calculated for the scalar model are in agreement
with the previously published results. We discuss possible manifestations of
separability for one meson exchange interaction kernels.Comment: 9 pages, 11 eps-figures. Talk presented by S. S. Semikh at XVII
International Baldin Seminar on High Energy Physics Problems "Relativistic
Nuclear Physics and Quantum Chromodynamics", September 27 - October 2, 2004,
Dubna, Russia; to appear in the proceedings of this conferenc
The effects of postexercise feeding on saliva antimicrobial proteins
The purpose of this study was to determine the effects of a carbohydrate (CHO) and protein (PRO) drink consumed immediately after endurance exercise on saliva antimicrobial proteins known to be important for host defense. Eleven male runners ran for 2 hr at 75% VO2max on 2 occasions and immediately postexercise were provided, in randomized order, either a placebo solution (CON) or a CHO-PRO solution containing 1.2 g CHO/kg body mass (BM) and 0.4 g PRO/kg BM (CHO-PRO). The solutions were flavor and volume equivalent (12 ml/kg BM). Saliva flow rate, lysozyme, α-amylase, and secretory (S) IgA concentrations were determined from unstimulated saliva samples collected preexercise, immediately postexercise, and every 30 min until 180 min postexercise. CHO-PRO ingestion immediately postexercise resulted in a lower saliva flow rate than with CON at 30 and 60 min postexercise. Saliva lysozyme concentration increased immediately postexercise in both trials compared with preexercise (p< .05), and CHO-PRO ingestion immediately postexercise resulted in a higher saliva lysozyme concentration in the first hour of recovery than with CON (125% greater at 30 min, 94% greater at 60 min; p< .01). Saliva SIgA concentration decreased below preexercise concentrations 90â150 min postexercise (p< .001), with no effect of CHO-PRO. Saliva α-amylase activity was unaffected by exercise or CHO-PRO refeeding. CHO-PRO refeeding did not alter the secretion rates of any saliva variables during recovery. In conclusion, immediate refeeding with CHO-PRO evoked a greater saliva lysozyme concentration during the first hour of recovery after prolonged exercise than ingestion of placebo but had minimal impact on saliva α-amylase and SIgA responses.</jats:p
Interaction of eukaryotic translation initiation factor 4G with the nuclear cap-binding complex provides a link between nuclear and cytoplasmic functions of the m7 guanosine cap
In eukaryotes the majority of mRNAs have an m7G cap that is added cotranscriptionally and that plays an important role in many aspects of mRNA metabolism. The nuclear cap-binding complex (CBC; consisting of CBP20 and CBP80) mediates the stimulatory functions of the cap in pre-mRNA splicing, 3' end formation, and U snRNA export. As little is known about how nuclear CBC mediates the effects of the cap in higher eukaryotes, we have characterized proteins that interact with CBC in HeLa cell nuclear extracts as potential mediators of its function. Using cross-linking and coimmunoprecipitation, we show that eukaryotic translation initiation factor 4G (eIF4G), in addition to its function in the cytoplasm, is a nuclear CBC-interacting protein. We demonstrate that eIF4G interacts with CBC in vitro and that, in addition to its cytoplasmic localization, there is a significant nuclear pool of eIF4G in mammalian cells in vivo. Immunoprecipitation experiments suggest that, in contrast to the cytoplasmic pool, much of the nuclear eIF4G is not associated with eIF4E (translation cap binding protein of eIF4F) but is associated with CBC. While eIF4G stably associates with spliceosomes in vitro and shows close association with spliceosomal snRNPs and splicing factors in vivo, depletion studies show that it does not participate directly in the splicing reaction. Taken together the data indicate that nuclear eIF4G may be recruited to pre-mRNAs via its interaction with CBC and accompanies the mRNA to the cytoplasm, facilitating the switching of CBC for eIF4F. This may provide a mechanism to couple nuclear and cytoplasmic functions of the mRNA cap structure
Role of retardation in 3-D relativistic equations
Equal-time Green's function is used to derive a three-dimensional integral
equation from the Bethe-Salpeter equation. The resultant equation, in the
absence of anti-particles, is identical to the use of time-ordered diagrams,
and has been used within the framework of coupling to study the
role of energy dependence and non-locality when the two-body potential is the
sum of -exchange and crossed exchange. The results show that
non-locality and energy dependence make a substantial contribution to both the
on-shell and off-shell amplitudes.Comment: 17 pages, RevTeX; 8 figures. Accepted for publication in Phys. Rev.
C56 (Nov. 97
- âŠ