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Periodicals - LEBANESE SCIENCE JOURNAL VOL.4, NO.2, 2003
Natural and Environmental Sciences
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Factors affecting nitrogen mineralization under laboratory conditions
with soils from a wheat-based rotation trial
J. Ryan, R. Hasbany, and T. Atallah
Mineralization of organic forms of nitrogen (N) in the field can
influence the amount of N available to crops and the response to
N fertilizer. The amount and rate of N mineralized in any season
is dependent on environmental factors, mainly moisture and temperature.
Total N in soils can vary with soil type and also as a result of
different cropping systems. A cereal rotation trial initiated in
1986 at the International Center for Agricultural Research in the
Dry Areas, (ICARDA) main research station, Tel Hadya, in northern
Syria, indicated that the cropping alternatives, especially forage
legumes, had induced changes in both soil organic matter and total
soil N. In order to assess the potential effect of mineralization
of total N on soil mineral N and crop growth, a series of laboratory
experiments were conducted to simulate environmental conditions
encountered in the field, i.e., the range of both temperature and
moisture and alternating wetting and drying that occurs in any rainfed
cropping system. In general, optimum mineralization occurred at
the higher temperatures (24–30ºC) and moisture content
of 100% field capacity. Repeated wetting and drying of soil samples
under constant temperature enhanced mineralization. There were substantial
differences between rotations, with soil from the medic rotation
consistently having the highest mineralization rate. These laboratory
observations corroborated data from the field trial reflecting increased
soil mineral N and crop N content and reduced crop response to applied
N. Back
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Chronological correlation of tracheal metapneumovirus antigenic distribution
to levels of specific humoral antibodies in broiler breeders and their
offspring
E. K. Barbour, F. Jirjis, O. Faroon, S. K. Hamadeh
and M. T. Farra
This study correlates chronologically the detection of antigenic distribution
of Metapneumovirus in ciliated brush border of tracheal surface epithelial
cells by direct immunofluorescence (IF) to detection of systemic humoral
Metapneumovirus-specific antibodies by indirect ELISA in four broiler
breeder flocks and their respective four broiler offspring flocks.
The chronological ratios of percentage (%) of positiveness (+ve) for
Metapneumovirus infection (% +ve by IF / % +ve by ELISA, P value for
significance of correlation) in breeders were: 3 wks before swollen
head syndrome (SHS) outbreak (0.0/0.0, P < 0.05), 2 wks before
SHS (28.6 / 0.0, P >0.05), 1 wk before SHS (71.4/0.0, P>0.05),
at initiation of SHS (67.9/0.0, P>0.05), 1 wk after initiation
of SHS (100/0.0, P>0.05), 2 wks after initiation of SHS (100/17.9,
P>0.05), 3 wks after initiation of SHS (100/67.9, P>0.05), and
4 wks after initiation of SHS (100/100, P < 0.05). However, the
chronological ratios in broiler offspring flocks were: 4 wks before
SHS outbreak (1 day of age) (0.0/100, P>0.05), 3 wks before SHS
(0.0/67.9, P>0.05), 2 wks before SHS (17.9/0.0, P>0.05), 1 wk
before SHS (71.4/0.0, P>0.05), at initiation of SHS outbreak (100/0.0,
P>0.05), 1 wk after initiation of SHS (100/0.0, P>0.05), and
2 wks after initiation of SHS (100/25, P>0.05). These findings
are indicative of the higher sensitivity of direct IF over indirect
ELISA in earlier diagnosis of Metapneumovirus infection in meat breeders
and their offsprings. Back
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Potentiel d’enracinement in vivo et in vitro de
variétés libanaises d’amandier (prunus dulcis
Miller)
L. Chalak, A. Elbitar, A. Chehadé, W. Chamoun
Cette étude a consisté à évaluer l’aptitude
à l’enracinement de 3 variétés libanaises
d’amandier (Prunus dulcis Miller), Firki, Halwani et Demi-khachabi.
Deux protocoles ont été comparés: le premier
réalisé en serre sur des rameaux lignifiés et
semi-lignifiés et sous l’action de concentrations croissantes
d'acide 3-indolylbutyrique; le second effectué sur des microboutures
préalablement multipliées in vitro, sous l’action
de 7 traitements différant par le type et la concentration
de l’auxine ainsi que par le mode d’induction. Les résultats
obtenus en serre ont révélé l’inefficacité
des traitements de l'acide 3-indolylbutyrique chez les 3 variétés,
quelle que soit la concentration utilisée. Dans les conditions
in vitro, l’enracinement des microboutures a été
réussi chez les 3 variétés, avec des taux dépassant
90%, après une phase d’induction à l’obscurité
pendant 4 h sous l’action de l'acide indole acétique
ou de l'acide 3-indolylbutyrique, suivie du transfert des microboutures
sur le milieu de Murashige et Skoog dépourvu de régulateurs
de croissance. Les microboutures ainsi enracinées ont été
acclimatées en serre avec un taux de reprise moyen de 60%.
Back
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Basic Sciences, Engineering and Technology
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Functional properties of the turbulent boundary layer
A. Zariankin, T. Chalhoub
A new approach is made to estimate the role of the turbulent boundary
layer. On the basis of the results of experiments carried out in the
laboratories of the Moscow Power Institute (MEI), complemented by
a theoretical analysis, the turbulent boundary layer is regarded as
a positive factor protecting the streamed surfaces from external perturbations,
and also protecting the external flow from the possible perturbations
generated by the vibrating wall. In this way, in the case of non-separated
flow, the construction elements of installation passages have a high
reliability due to the protective property of the turbulent boundary
layer. Back
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Reversible integer-to-integer
wavelet transforms for image compression: implementation and evaluation
M. A. Ben Ayed, M. Loulou, N. Masmoudi, L. Kamoun
There has been a growing interest in the reversible integer to integer
wavelet transforms for image coding. In this paper, several of those
particular transforms are integrated using a VHDL description on a
FPGA circuit. Two different architectures are proposed, one uses the
lifting framework as an architectural support and the other takes
advantage of the two finite impulse response filter (FIR) structures
representing the wavelet transform function. Evaluation is performed
on the basis of their computational complexity, latency, hardware
occupancy, and finally maximum operating clock frequency of the circuit
obtained. Of the transforms considered, some of them seem to perform
particularly well depending on the architecture used. Back
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Etude par chromatographie gaz inverse des propriétés
superficielles de quelques charges minérales
B.
Hamdi, S. Hamdi, Z. Kessaïssia
Au cours de cette étude, nous avons suivi par chromatographie
gaz inverse à dilution infinie l'évolution de la composante
dispersive de l'énergie de surface (γds
) de quelques charges minérales naturelles et synthétiques
avant et après traitement chimique. L'étude a révélé
que la surface énergétique d'une charge dépend
étroitement de la surface chimique, morphologique et nanomorphologique.
Une bonne corrélation est obtenue entre l'énergie de
surface et la fonctionnalité de surface, la surface spécifique
et les impuretés minérales. D'autre part, l'étude
a montré que γdsdes silices modifiées
par des polymères linéaires ou articulés dépend
étroitement du taux de polymère lié chimiquement.
Back
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Experimental results of a fabricated analog VLSI multiplier/transconductance
circuit
H. Chiblé
In this paper, a fabricated analog VLSI Circuit is presented, which
can be used as a four quadrant analog multiplier with high linearity
on both terms of multiplication and wide range on one of them. These
characteristics make the circuit useful for the implementation of
a transconductance. The transconductance/multiplier can be used
for general purpose in analog signal processing, but the circuit
is suitable for Analog VLSI implementation of artificial neural
networks because of its small silicon area and its low power consumption.
The theoretical idea and the simulation by using Hspice are presented
in (Chiblé, 2000), which is improved, fabricated and tested
in this paper. The experimental results are presented. Back
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Système numérique de la mécanique déterministe
M. Al-Houjairi
Les systèmes numériques représentent des modèles
mathématiques idéalisés quasi-adéquats
aux rapports quantitatifs dans le monde réel. Le présent
travail est orienté à mettre les accents sur quelques
aspects du déterminisme au cours du développement
théorique de la conception du nombre.
Or toutes les théories des nombres réels sont équivalentes,
bien qu'elles soient d'origines et de motivations distinctes. Dans
le présent travail, nous essayons de mettre l'accent sur
le fait que l'équivalence de ces différentes théories
n'est pas le fruit du hasard mais c'est la conséquence d'un
certain déterminisme. Les principaux facteurs du déterminisme
dans la construction du corps R sont conditionnés par l'exigence
en mécanique de l'unicité de la trajectoire d'un mouvement
à conditions initiales données. Back
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