2,992 research outputs found
Yields and qualities of pigeonpea varieties grown under smallholder farmers’ conditions in Eastern and Southern Africa
Pigeonpea is one of the few crops with a high potential for resource-poor farmers due to its complementary resource use when intercropped with maize. A three year comprehensive comparative study on the performance of six pigeonpea (Cajanus cajan) varieties on farmers’ fields in Eastern and Southern Africa where intercropping with maize is normal practice, was undertaken. The varieties were tested for accumulation of dry matter (DM), nitrogen (N) and phosphorus (P) in all above-ground organs for three years under farmers’ conditions. The study revealed that the latest introduced ICEAP 00040 outperformed all the other tested varieties (ICP 9145; ICEAP 00020, ICEAP 00053, ICEAP 00068, and a local variety called “Babati White”) under farmer-managed conditions. The harvest indices (HI), ranging from 0.08-0.15 on dry matter (DM) basis, were relatively low and unaffected (P>0.05) by the environmental variation. The N harvest index (NHI) was 0.28 and P harvest index (PHI) was 0.19. The better responses of ICEAP00040 to favourable conditions could however only be realised in a minority of cases as yields generally were low. These low yields are still a major challenge in African smallholder agriculture as pulses play an important role in soil fertility maintenance as well as in the household diets
Three-Body Halos. II. from Two- to Three-Body Asymptotics
The large distance behavior of weakly bound three-body systems is
investigated. The Schr\"{o}dinger equation and the Faddeev equations are
reformulated by an expansion in eigenfunctions of the angular part of a
corresponding operator. The resulting coupled set of effective radial equations
are then derived. Both two- and three-body asymptotic behavior are possible and
their relative importance is studied for systems where subsystems may be bound.
The system of two nucleons outside a core is studied numerically in detail and
the character of possible halo structure is pointed out and investigated.Comment: 16 pages, compressed and uuencoded PosrScript file, IFA-94/3
On the stability of black hole event horizons
In this work we study a {\it gedanken} experiment constructed in order to
test the cosmic censorship hypothesis and the second law of black hole
thermo-dynamics. Matter with a negative gravitating energy is imagined added to
a near extremal -charged static black hole in Einstein-Maxwell theory.
The dynamics of a similar process is studied and the thermo-dynamical
properties of the resulting black hole structure is discussed. A new mechanism
which stabilizes black hole event horizons is shown to operate in such
processes.Comment: 16, grammatical errors corrected and two references adde
The coefficient of correction of effectiveness with the account of natural factors
The existing methods of determination of effectiveness don’t give the opportunity to emphasize the factors to the
full extent. By which we can achieve the effect: the level of development of technologies, exploitation of natural
resources, i,e. the damage to the environment etc. The economic damage, caused to the environment as a result of
exploitation of natural resources and ecological violations at the given moment, doesn’t have a precise definition at the
profound level.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/1280
Spectral graph theory efficiently characterizes ventilation heterogeneity in lung airway networks
This paper introduces a linear operator for the purposes of quantifying the spectral properties of transport within resistive trees, such as airflow in lung airway networks. The operator, which we call the Maury matrix, acts only on the terminal nodes of the tree and is equivalent to the adjacency matrix of a complete graph summarizing the relationships between all pairs of terminal nodes. We show that the eigenmodes of the Maury operator have a direct physical interpretation as the relaxation, or resistive, modes of the network. We apply these findings to both idealized and image-based models of ventilation in lung airway trees and show that the spectral properties of the Maury matrix characterize the flow asymmetry in these networks more concisely than the Laplacian modes, and that eigenvector centrality in the Maury spectrum is closely related to the phenomenon of ventilation heterogeneity caused by airway narrowing or obstruction. This method has applications in dimensionality reduction in simulations of lung mechanics, as well as for characterization of models of the airway tree derived from medical images
Irrigation Scheduling for Optimum Water Management
Irrigation scheduling is rapidly gaining acceptance as a valuable tool for
developing an on-farm water management program. Irrigation scheduling
develops the optimum timing and amounts of irrigation applications and provides
the ability to manage the soil-moisture reservoir. Improving the
timing and amounts of irrigation applied will reduce the adverse environmental
effects of irrigated agriculture. Improved management of the soil-moisture
reservoir directly benefits the irrigator economically. A computer
is used to maintain a daily water budget, give the current status of the
soil-moisture reservoir, and predict evapotranspiration for the next 14 days.
Data required are basic soil-moisture properties, estimated rate of crop
development, and daily climatic data. By applying these parameters as
they individually and comprehensively relate to an irrigation project and the
local cultural practices, an optimum irrigation schedule can be developed.
This schedule gives attention to the many decision considerations that an
irrigator needs to make in his day-to-day operation
Interface Depinning in the Absence of External Driving Force
We study the pinning-depinning phase transition of interfaces in the quenched
Kardar-Parisi-Zhang model as the external driving force goes towards zero.
For a fixed value of the driving force we induce depinning by increasing the
nonlinear term coefficient , which is related to lateral growth, up to
a critical threshold. We focus on the case in which there is no external force
applied (F=0) and find that, contrary to a simple scaling prediction, there is
a finite value of that makes the interface to become depinned. The
critical exponents at the transition are consistent with directed percolation
depinning. Our results are relevant for paper wetting experiments, in which an
interface gets moving with no external driving force.Comment: 4 pages, 3 figures included, uses epsf. Submitted to PR
Interface Scaling in the Contact Process
Scaling properties of an interface representation of the critical contact
process are studied in dimensions 1 - 3. Simulations confirm the scaling
relation beta_W = 1 - theta between the interface-width growth exponent beta_W
and the exponent theta governing the decay of the order parameter. A scaling
property of the height distribution, which serves as the basis for this
relation, is also verified. The height-height correlation function shows clear
signs of anomalous scaling, in accord with Lopez' analysis [Phys. Rev. Lett.
83, 4594 (1999)], but no evidence of multiscaling.Comment: 10 pages, 9 figure
Bipolar querying of valid-time intervals subject to uncertainty
Databases model parts of reality by containing data representing properties of real-world objects or concepts. Often, some of these properties are time-related. Thus, databases often contain data representing time-related information. However, as they may be produced by humans, such data or information may contain imperfections like uncertainties. An important purpose of databases is to allow their data to be queried, to allow access to the information these data represent. Users may do this using queries, in which they describe their preferences concerning the data they are (not) interested in. Because users may have both positive and negative such preferences, they may want to query databases in a bipolar way. Such preferences may also have a temporal nature, but, traditionally, temporal query conditions are handled specifically. In this paper, a novel technique is presented to query a valid-time relation containing uncertain valid-time data in a bipolar way, which allows the query to have a single bipolar temporal query condition
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