Teneurs en 18O et concentration saline d'eaux paraliques et continentales égyptiennes

Plusieurs corps d'eau lagunaires et continentaux égyptiens sont comparés quant à l'abondance en oxygène-18 et la concentration saline (ici appréciée par la teneur en Cl¯) de leurs eaux superficielles.En Egypte, les eaux continentales de surface proviennent toutes du système nilotique dont les eaux, après leur longue traversée du grand Desert Oriental, se trouvent très évaporées et fortement enrichies en oxygène-18 à leur arrivée dans le delta.Dans les bassins alimentés uniquement par la mer (lagunes de Mer Rouge et du Golfe de Suez) soit par l'eau du Nil (Lac du Fayoum), les deux paramètres considérés augmentent conjointement depuis les zones d'alimentation vers les reculées marginales selon le déplacement des eaux.Dans les bassins à alimentation mixte, (Partie terminale du delta, lac Temsah sur le Canal de Suez), les eaux les plus diluées sont aussi les plus riches en isotopes lourds.Ainsi, dans le contexte climatique et géographique très particulierde l'Egypte, il est possible de reconnaître les eaux continentales, marines ou paraliques à partir des deux paramètres étudiés mais non à partir d'un seul, notamment la teneur en oxygène-18.The aim of this paper is to study some aspects of the geochemical behaviour (18O, (Cl-)) of waters of some basins in Egypt. Several types of basin are studied (figure 1).1) Basin with marine seawater input only, either wide open to the Red sea such as Zeit Bay (27°45'N, 33°25'E), relatively open such as Guesmah Lagoon (27°40'N, 33°30'E) or indirectly linked to the sea through a coastal sand bar such as the pools of sebkha Melaha (28°10'N, 33°10'E).2) Basin supplied by continental water without outflow such as Fayoum Lake (= Birket Karoum) (29°25'N, 30°30'E) which receives fresh waters from a Nile diversion.3) Water bodies with a mixed water input (continental and marine waters) such as the Nile delta and Temsah Lake (= Ismaïla Lake), (30°25'N, 31°30'E), the katter being on the Suez Canal and receiving waters from Mediterranean Sea and from the eastern branch of the Nile.Local means climatic parameter are those of Cairo, Alexandria, Queseir and Louxor (table 1).RESULTS AND DISCUSSION1 - Nile delta (figure 2 and 3)Sampling period was performed in August 1984.- At the beginning of the Nile delta the water at Beni-Suez (station 14) presents a low chloride concentration (0.1 to 0.2 g l-1) and a relatively high 18O content (+ 3 ‰) due to evaporation of the Nile water during its downstream course from the Aswan High Dam which collects waters in the upper part of the Nile watershed.- The content of both (Cl-) and 18O stightly increases in the delta region in relation to the anastomosis of branches of the Nile due to an intensive irrigation network.- In the coastal region, due to mixing with sea water or/and brackish water, the isotope content decreases while the chloride concentration increases.2 - Temsah or Ismaïla LakeTwo periods of sampling : March and August 1984. The general trend is a decrease of 18O and an increase of (Cl-) from the Nile waters to the central part of the lake, and an increase of both 18O and (Cl-) at the fringes of the lake, due to evaporation.3 - Coastal basins from the Red SeaZeit Bay and Guesmah Lagoon. Two sampling periods : March and August 1984. The isotope content and chloride concentration act in parallel and depend principally on the movement of water bodies. For the surface waters wind velocity and direction play a major rote in the spatial distribution of the chlorinity and isotope content. A slight enrichment is noted during the summer period.4 - Pools in Sebkha MelahaThe isotope composition and chloride content of the ponds water fed by sea water through the sand salt bar increased during the summer as it is the case in the first stages of evaporation of salt pans (PIERRE and FONTES, 1982).5 - Fayoun Lake : Birket KaroumTwo sampling periods : March and August 1984. Because of a lack of sufficient data (salinity and isotopic composition of the input, water flux of the incoming water, local values of the relative humidity and temperature of the atmosphere, isotopic composition of the water vapour...) a water mass balance coupled with a chloride and isotopic mass balance was not possible. Nevertheless, with our data measured (18O, (Cl-) lake levels), some estimations were made of the temperature, evaporation, wind velocities (from meteorological tables) and the isotopic composition of the input : δA in the lake (SIMPSON et al., 1987), and if we assume that the lake presents a long term dynamic equilibrium, it is possible to estimate with reasonable accuracy that : i) the total isotopic enrichment factor (ɛ) is between 8 ‰ and 24 ‰ (figure 12) : ɛ= ɛe + ɛk , with ɛe = equilibrium isotopic enrichment factor; ɛk = kinetic isotopic enrichment factor. ii) the salt content of the incoming water δA is ≈20 g l-1. The principal consequence is that the important loss of water observed between the sampling periods (1.5 m difference in water level) was not due to evaporation only, but more by seepage from the bottom of the take (≈ 560 106 m3 for a total volume of ≈800 106 m3).CONCLUSIONS1) On a diagram δ18O - CL- (figure 13 and 14) where all the data for the Egyptian basins studied are represented, the similarity in the geochemical behaviour of the basins with a single input, is noted; the relation between isotopic composition and chloride content is approximatively logarithmic. In the case of a mixed input basin (Temsah Lake) two branches on the diagram are distinct; the first branch shows the effect of mixing in the west part of the lake, between evaporated Nile water and water from the Mediterranean Sea. The shape of this branch is very similar to that of the Nile delta: the second branch represents evaporation in the east part of the take (figure 13 and 14).2) In the case of a semi-arid environment, this study shows that with two simple parameters only, such as isotopic composition and the chloride content of waters, it is possible to distinguish the marine, paralic and continental domain (figure 15)

Efficacy of plant extracts in controlling wheat leaf rust disease caused by Puccinia triticina

AbstractThe efficacy of eight plant extracts (garlic, clove, garden quinine, Brazilian pepper, anthi mandhaari, black cumin, white cedar and neem) in controlling leaf rust disease of wheat was investigated in vitro and in vivo. In vitro, all treatments inhibited spore germination by more than 93%. Neem extract recorded 98.99% inhibition of spore germination with no significant difference from the fungicide Sumi-8 (100%). Under greenhouse conditions, seed soaking application in neem extract (at concentration of 2ml/L) resulted in 36.82% reduction in the number of pustules/leaf compared with the untreated control. Foliar spraying of plant extracts on wheat seedlings decreased the number of pustules/leaf. Foliar spraying of plant extracts four days after inoculation led to the highest resistance response of wheat plants against leaf rust pathogen. Spray application of wheat seedlings with neem, clove and garden quinine extracts, four days after inoculation with leaf rust pathogen completely prevented rust development (100% disease control) and was comparable with the fungicide Sumi-8. Foliar spray application of wheat plants at mature stage with all plant extracts has significantly reduced the leaf rust infection (average coefficient of infection, ACI) compared with the untreated control and neem was the most effective treatment. This was reflected on grain yield components, whereas the 1000-kernel weight and the test weight were improved whether under one- or two-spray applications, with two-spray application being more effective in this regard. Thus, it could be concluded that plant extracts may be useful to control leaf rust disease in Egypt as a safe alternative option to chemical fungicides

Normalization factors for magnetic relaxation of small particle systems in non-zero magnetic field

We critically discuss relaxation experiments in magnetic systems that can be characterized in terms of an energy barrier distribution, showing that proper normalization of the relaxation data is needed whenever curves corresponding to different temperatures are to be compared. We show how these normalization factors can be obtained from experimental data by using the $T \ln(t/\tau_0)$ scaling method without making any assumptions about the nature of the energy barrier distribution. The validity of the procedure is tested using a ferrofluid of Fe_3O_4 particles.Comment: 5 pages, 6 eps figures added in April 22, to be published in Phys. Rev. B 55 (1 April 1997

A Precision Measurement of the Neutron Twist-3 Matrix Element d2nd_2^n: Probing Color Forces

Double-spin asymmetries and absolute cross sections were measured at large Bjorken $x$ (0.25 $\le x \le$ 0.90), in both the deep-inelastic and resonance regions, by scattering longitudinally polarized electrons at beam energies of 4.7 and 5.9 GeV from a transversely and longitudinally polarized $^3$He target. In this dedicated experiment, the spin structure function $g_2$ on $^3$He was determined with precision at large $x$, and the neutron twist-three matrix element $d_2^n$ was measured at \left of 3.21 and 4.32 GeV$^2$/$c^2$, with an absolute precision of about $10^{-5}$. Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at \left = 5 GeV$^2$/$c^2$. Combining $d_2^n$ and a newly extracted twist-four matrix element, $f_2^n$, the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 30 MeV/fm in magnitude.Comment: Corrected a typo in the author list and Figure 1 legend. 6 pages, 2 figures, 2 table

The European Union in the World — A Community of Values

These are momentous times in Europe. The Euro has been successfully introduced, the enlargement negotiations are approaching their climax, and the European Convention (“Convention”) is moving towards the drafting of a constitution for a new, continent-wide political entity. At the same time, unrest is manifest, particularly in two areas. On the one hand, many of our citizens, and not just the political elites, are dissatisfied with Europe\u27s performance on the world stage and are concerned about the maintenance of peace and security within the Union. In these areas they would like to see a strengthened, more effective entity-- “more Europe.” On the other hand, their disenchantment with the long reach of European Union (“EU” or “Union”) regulation in the first pillar area of economic policy is growing. The feeling of loss of local control over their destiny and a vague feeling of potential loss of identity within an ever more centralized polity is palpable. Here, they want “less Europe.” In the outside world, change is also the order of the day. The ice-sheet of bipolarity, which overlaid and hid the complexity of international relations during the Cold War, is breaking up at an ever-increasing speed and revealing a world in which two paradigms are competing to become the underlying ordering principles for the new century. The traditional paradigm of interacting Nation States, each pursuing its own separate interests, with alliances allowing the small to compete with the large, is alive and well, and its proponents like Machiavelli or Churchill continue to be in vogue in the literature of international relations and the rhetoric of world leaders. At the same time, there is a school of thought which points to the growing economic and ecological interdependence of our societies and the necessity for new forms of global governance to complement national action. It is also becoming abundantly clear that the concept of a “Nation State” is often a fiction, positing as it does an identity between the citizens of a State and the members of a culturally homogenous society. For both reasons, the concept of the Nation State as the principal actor on the world stage, is called into question. The experience of the Union with the sharing of State sovereignty is clearly related to the second paradigm and also to the EU\u27s firm support for the development of the United Nations (“U.N.”) as well as other elements of multilateral governance. It would hardly be wise to suggest that any foreign policy, and certainly not that of the EU, should be based only on this paradigm. Given the recurrent threats to security, which seem to be part of the human condition expressed by some as the “inevitability of war”--the defense of territorial integrity; action against threats of aggression; and resistance to crimes against humanity such as genocide--the ability to conduct a security policy based much more on the old paradigm of interacting interests will continue to be required. That the EU needs to develop such a capability will be taken here as a given. Such a crisis-management capability will be essential to the Union, but will be distinguished here from the more long-term elements of foreign policy, which can be thought of as being designed to reduce the need for crisis management in the context of a security policy to a minimum. The crisis-management area of policy will not be treated further here. The thesis of this Essay is that the same set of political concepts can serve as a guide to the future internal development of the EU and as the basis of such a long-term foreign policy. Furthermore, it suggests that neither should be seen in terms of the balancing of interests but rather, as the expression of a small list of fundamental values. The list is as follows: (1) the rule of law as the basis for relations between members of society; (2) the interaction between the democratic process and entrenched human rights in political decision-making; (3) the operation of competition within a market economy as the source of increasing prosperity; (4) the anchoring of the principle of solidarity among all members of society alongside that of the liberty of the individual; (5) the adoption of the principle of sustainability of all economic development; and (6) the preservation of separate identities and the maintenance of cultural diversity within society. These values can be seen as the answer to the question posed both, by citizens of the Union and by our fellow citizens of the world: “What does the EU stand for?” In exploring these values we should, however, remember that in the real world there will be occasions on which Realpolitik will intrude and the interest-based paradigm will prevail

Eating Habits and Lifestyles among a Sample of Obese Working Egyptian Women

BACKGROUND: The fundamental cause of obesity and overweight is an energy imbalance between calories consumed and calories expended.AIM: To figure out food habits and different lifestyle pattern among a sample of Egyptian females working at the National Research Centre.METHODS: A cross-sectional, descriptive study, including 138 overweight and obese Egyptian females (BMI ≥ 25 Kg/m2); working at the National Research Centre; was done. A specific questionnaire was used to gather information regarding lifestyle including dietary habits, physical activity and sedentary behaviour. RESULTS: The prevalence of overweight among the studied subjects was 27%, while that of obesity was 38%. Missing and or infrequent intake of breakfast at home, frequent consumption of snacks, low serving per day of fruits and vegetables with frequent consumption of sweets, fried food, eating while watching TV and sedentary behaviour were all predictors of obesity and overweight among the current sample.CONCLUSION: The present study identified several lifestyle factors and improper dietary habits associated with overweight and obesity among Egyptian females. There is a great need to change these habits to avoid the increasing risk of obesity. A national plan of action to overcome obesity is urgently needed to reduce its economic and health burden

Measurement of pretzelosity asymmetry of charged pion production in Semi-Inclusive Deep Inelastic Scattering on a polarized 3^3He target

An experiment to measure single-spin asymmetries in semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized $^3$He target was performed at Jefferson Lab in the kinematic region of $0.16<x<0.35$ and $1.4<Q^2<2.7$ ${\rm GeV^2}$. The pretzelosity asymmetries on $^3$He, which can be expressed as the convolution of the $h^\perp_{1T}$ transverse momentum dependent distribution functions and the Collins fragmentation functions in the leading order, were measured for the first time. Using the effective polarization approximation, we extracted the corresponding neutron asymmetries from the measured $^3$He asymmetries and cross-section ratios between the proton and $^3$He. Our results show that for both $\pi^{\pm}$ on $^3$He and on the neutron the pretzelosity asymmetries are consistent with zero within experimental uncertainties.Comment: 6 pages, 3 figures; enlarged the legends in Fig.3; added 3 citation

Double Spin Asymmetries of Inclusive Hadron Electroproductions from a Transversely Polarized 3He^3\rm{He} Target

We report the measurement of beam-target double-spin asymmetries ($A_\text{LT}$) in the inclusive production of identified hadrons, $\vec{e}~$+$~^3\text{He}^{\uparrow}\rightarrow h+X$, using a longitudinally polarized 5.9 GeV electron beam and a transversely polarized $^3\rm{He}$ target. Hadrons ($\pi^{\pm}$, $K^{\pm}$ and proton) were detected at 16$^{\circ}$ with an average momentum $$=2.35 GeV/c and a transverse momentum ($p_{T}$) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the $^3\text{He}$ target were observed to be non-zero for $\pi^{\pm}$ production when the target was polarized transversely in the horizontal plane. The $\pi^{+}$ and $\pi^{-}$ asymmetries have opposite signs, analogous to the behavior of $A_\text{LT}$ in semi-inclusive deep-inelastic scattering.Comment: Published in PRC (92.015207), nuclear experiment, high-energy experimen

Single Spin Asymmetries of Inclusive Hadrons Produced in Electron Scattering from a Transversely Polarized 3^3He Target

We report the first measurement of target single-spin asymmetries (A$_N$) in the inclusive hadron production reaction, $e~$+$~^3\text{He}^{\uparrow}\rightarrow h+X$, using a transversely polarized $^3$He target. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons ($\pi^{\pm}$, $\text{K}^{\pm}$ and proton) were detected in the transverse hadron momentum range 0.54 $<p_T<$ 0.74 GeV/c. The range of $x_F$ for pions was -0.29 $<x_F<$ -0.23 and for kaons -0.25 $<x_F<$-0.18. The observed asymmetry strongly depends on the type of hadron. A positive asymmetry is observed for $\pi^+$ and $\text{K}^+$. A negative asymmetry is observed for $\pi^{-}$. The magnitudes of the asymmetries follow $|A^{\pi^-}| < |A^{\pi^+}| < |A^{K^+}|$. The K$^{-}$ and proton asymmetries are consistent with zero within the experimental uncertainties. The $\pi^{+}$ and $\pi^{-}$ asymmetries measured for the $^3$He target and extracted for neutrons are opposite in sign with a small increase observed as a function of $p_T$.Comment: Updated version, submitted to Phys. Rev.