Showing papers by "University of Jordan published in 2000"

Slip rate on the Dead Sea transform fault in northern Araba valley (Jordan)

Abstract: The Araba valley lies between the southern tip of the Dead Sea and the Gulf of Aqaba. This depression, blanketed with alluvial and lacustrine deposits, is cut along its entire length by the Dead Sea fault. In many places the fault is well defined by scarps, and evidence for left-lateral strike-slip faulting is abundant. The slip rate on the fault can be constrained from dated geomorphic features displaced by the fault. A large fan at the mouth of Wadi Dahal has been displaced by about 500 m since the bulk of the fanglomerates were deposited 77–140 kyr ago, as dated from cosmogenic isotope analysis (^(10)Be in chert) of pebbles collected on the fan surface and from the age of transgressive lacustrine sediments capping the fan. Holocene alluvial surfaces are also clearly offset. By correlation with similar surfaces along the Dead Sea lake margin, we propose a chronology for their emplacement. Taken together, our observations suggest an average slip rate over the Late Pleistocene of between 2 and 6 mm yr^(−1), with a preferred value of 4 mm yr^(−1). This slip rate is shown to be consistent with other constraints on the kinematics of the Arabian plate, assuming a rotation rate of about 0.396° Myr^(−1) around a pole at 31.1°N, 26.7°E relative to Africa.

Sealing ability of amalgam, super EBA cement, and MTA when used as retrograde filling materials

Abstract: Objective To compare apical microleakage of MTA following reverse retrograde root filling with that following amalgam and EBA retrofilling. Design Prospective random control trial. Setting It was conducted at the University of Jordan in 1998. Materials and methods The root canals of 79 extracted teeth were instrumented and obturated with vertically condensed gutta-percha. Each tooth was apically resected and the apex was prepared ultrasonically to 3 mm depth and the root surface isolated with nail varnish. Teeth were divided randomly into three groups of 25 teeth each. First group was retrofilled with amalgam, second group with EBA and the third group with MTA. Following immersion in 1% methylene blue dye for 72 hours, the roots were sectioned and the depth of dye penetration was evaluated by a stereomicroscope at x10 magnification. Interventions Super EBA is a reinforced zinc oxide cement based on a mixture of 32% eugenol and 68% ethoxy benzoic acid (EBA). MTA is a mineral trioxide aggregate cement (MTA) based on a mixture of sterile water. Main outcome measures The sealing effectiveness of the retrograde filling materials used in this study was determined by their ability to inhibit dye penetration. Results 56% of the group filled with amalgam and 20% of the group filled with EBA showed dye leakage beyond the retrofilling material whereas the MTA group showed none, two samples from MTA group were eliminated because of their fractured roots. The chi-squared test revealed a statistically significant difference among all three groups (P < 0.05). Conclusion MTA cement provides a better seal than amalgam and EBA cement when used as retrograde filling, but the extrapolation of this result into a clinical practice may be questionable.

Seismic behaviour of the Dead Sea fault along Araba valley, Jordan

Abstract: The Dead Sea fault zone is a major left-lateral strike-slip fault. South of the Dead Sea basin, the Wadi Araba fault extends over 160 km to the Gulf of Aqaba. The Dead Sea fault zone is known to have produced several relatively large historical earthquakes. However, the historical events are unequally distributed along the fault and only four events have been reported in the Araba valley over the last few thousands of years. Magnitudes estimated from the historical record are probably slightly smaller than that of the M_w ∼ 7.3 earthquake that struck the Gulf of Aqaba in 1995. The fault cuts straight across Pleistocene to Holocene alluvium and shows morphologic evidence for essentially pure strike-slip motion. Regional seismic monitoring reveals little microseismicity along the fault except around the Dead Sea and Gulf of Aqaba, where the fault splays into complex pull-apart basin fault systems. We have investigated the fault zone at several sites selected from SPOT images and the study of aerial photography. At the site of the now destroyed Tilah Castle, a well-preserved wall, dated to be about 1200 yr BP (^(14)C age on charcoal), is cut by the fault and offset by 2.2 m. Comparison with offset gullies at a nearby site 3 km to the north and at three other sites, respectively 25, 50 and 65 km to the south, reveals that this specific fault displacement is probably related to the last seismic event that ruptured that fault segment, possibly in AD 1458. Moreover, the offset gullies suggest a characteristic slip behaviour with recurring slip of about 1.5 m on average. Given the 4 ± 2 mm yr^(−1) slip rate derived for this fault segment, we infer that the fault should produce M_w ∼ 7 earthquakes along some segment in the Araba valley about every 200 years. The historical period, with only four well-documented large earthquakes in AD 1068, AD 1212, AD 1293 and AD 1458, thus appears to have been relatively quiescent, with a 20 per cent deficit of M_w ∼ 7 earthquakes. However, our data do not exclude the possibility of larger M_w ∼ 7.6 earthquakes or time clustering of earthquakes over longer timespans. An alternative seismic behaviour involves M_w ∼ 7.6 earthquakes about every 6000 years and M_w ∼ 7 earthquakes about every 250 years. The historical catalogue would then appear to be complete for M_w ∼ 7 earthquakes.

Microemulsions are membrane‐active, antimicrobial, self‐preserving systems

Abstract: Microemulsions are physically stable oil/water systems that have potential use as delivery systems for many pharmaceuticals which are normally of limited use due to their hydrophobicity, toxicity or inability to access the site of action. It has been suggested that microemulsions are self-preserving antimicrobials in their own right, although there is little evidence to support this. In this experiment, microemulsions of various compositions were formulated and tested for their stability and antimicrobial action. The physical stability of the different microemulsions was assessed by centrifugation at 4000g and by storage in a water bath at 37 degrees C for one month, during which no phase separation was observed. The antimicrobial activity of the microemulsions was tested using the compendial method, observation of the kinetics of killing, and transmission electron microscopy (TEM) of microemulsion-exposed cultures of Pseudomonas aeruginosa PA01. These latter experiments on Ps. aeruginosa indicated distinct signs of membrane disruption. The results indicated that the microemulsions are self-preserved, and that their killing of microbial cultures is very rapid and may be the result of membrane activity.

Exposure of human erythrocytes to oxygen radicals causes loss of deformability, increased osmotic fragility, lipid peroxidation and protein degradation.

Abstract: The effects of two oxygen radical generating systems (H 2 O 2 and ascorbate/Fe +2 ) on erythrocyte deformability, osmotic fragility, lipid peroxidation and protein degradation were studied. Incubation of erythrocytes with different concentrations of H 2 O 2 (5-20 mM) or ascorbate/Fe +2 (10/0.1-40/0.4 mM) caused a loss of deformability and increased osmotic fragility. The loss of deformability has occurred in a dose-dependent fashion and was proportional to the extent of malonyldialdehyde (an indicator of lipid peroxidation) and alanine production (an indicator of protein degradation). Prior exposure of the erythrocytes to carbon monoxide (known to inhibit heme-protein degradation) prevented almost completely the loss in deformability caused by H 2 02, indicating that the loss in deformability was due mainly to protein degradation rather than to lipid peroxidation. Erythrocytes incubated with either of the two systems have also shown morphologic changes characterized by a dose-dependent increase in echinocyte formation. The results indicate the importance of oxidatively damaged proteins in compromising the rheologic behaviour of the erythrocytes, particularly when the free radicals are involved.

The Feasibility of Using Diatomite and Mn–Diatomite for Remediation of Pb2+, Cu2+, and Cd2+ from Water

Abstract: Diatomite and manganese-oxide-modified–diatomite (Mn–diatomite) were tested as adsorbents for Pb2+, Cu2+, and Cd2+removal from water. Impregnating the surface of diatomite with 0.38 g of manganese oxide per gram diatomite shows an increase of 2.4-fold in the surface area of the modified diatomite. The adsorption capacities were 99, 51, and 26 mg/g Mn–diatomite for Pb2+, Cu2+,and Cd2+, respectively, obtained at solution pH 4, while values of 24, 21, and 16 mg/g diatomite were obtained at the same conditions and for the same metals. The obtained adsorption kinetics experimental data display that 95% of the original Pb2+ concentrated was adsorbed by Mn–diatomite within 10 min, while kinetic data for diatomite showed a lower rate for Pb2+ uptake. The filtration quality of diatomite was significantly enhanced with the surface modification by manganese oxide.

Cytological and molecular evidence that the whitefly-transmitted cucumber vein yellowing virus is a tentative member of the family Potyviridae.

Abstract: Cucumber vein yellowing virus (CVYV) is widespread in cucurbits in the Middle East. CVYV has filamentous particles and is transmitted by Bemisia tabaci by the semi-persistent mode. It has not yet been assigned to a specific genus or family. Ultramicroscopic observations revealed numerous cylindrical cytoplasmic inclusions in melon and cucumber cells infected by CVYV isolates from Israel and Jordan. Depending on the section orientation, the inclusions appeared as pinwheels or as bundles. In addition, a 1·9 kb DNA fragment was amplified by RT–PCR from CVYV-infected plant extracts using primers designed to detect all potyvirids. Sequence comparisons with the amplified fragment indicated that CVYV is more closely related to Sweet potato mild mottle virus than to any other virus in the family Potyviridae. These results suggest that CVYV can be considered as a tentative new member of the genus Ipomovirus, family Potyviridae.

Optimal use of irrigation water in the Jordan Valley : A case study

Abstract: Water shortage is a serious problem in most countries in theMiddle East. Irrigation water consumes about three-fourths of theavailable fresh water resources in Jordam and many othercountries in the region. This article presents a practical approachto manage and optimize the irrigation water use in the region.The ultimate objective is to minimize the outside water and tomanage the irrigation water use under geographic,socio-economic, and demographic constraints. This approach usesthe added value (net revenue) of one cubic meter of waterconcept in evaluating different irrigation water use management.This concept has been demonstrated, based on a case study in theJordan Valley.This case study shows that water scarcity can be incorporated inirrigation water management by proper choice of crops andfarming patters. The objective function is to maximize the netrevenue from the agricultural production process subjected tolimitation on water and other production and marketing factors.Results of analysis showed that a net water saving of about9%occurred if the objective function is to minimize water useunder the same level of profitability. This example shall beuseful for water and agricultural planners. Sometimes virtualwater is widely exported in form of crops that consumes largeamounts of water without full economic consideration to theadded value of water. In some cases, food imports may be afeasible option in water-poor countries instead of water import.

Consanguinity, fertility, reproductive wastage, infant mortality and congenital malformations in Jordan.

Abstract: OBJECTIVES Consanguinity is a wide spread practice in Jordan. The objective of this study is to explore the health effects of consanguinity, in particular fertility, reproductive wastage, infant mortality and congenital malformations. METHODS A stratified 2 stage cluster sample of 1867 married couples, representative of all population groups and all geographic locations of Jordan were randomly selected. A questionnaire was specially designed to explore each of the objectives set for the study and was field tested. A group of field workers were thoroughly trained on the implementation of this instrument. All 1867 couples were interviewed by these field workers and completed questionnaires were reviewed before data entry. Data analysis was carried out using SPSSX statistical package. Significance tests were performed wherever appropriate. RESULTS The study showed that fertility, as measured by the number of pregnancies, taking into consideration marriage duration, was not affected by consanguinity. Twin pregnancies and abortions did not show any significant difference between consanguineous and non-consanguineous marriages. Consanguineous marriages showed significantly higher rates of still births and infant mortality in general. Within the consanguineous group, female infant mortality rates were significantly higher than those of males. Congenital malformations as reported by mothers of consanguineous marriages were significantly higher than those reported by mothers of non-consanguineous marriages. CONCLUSIONS This study showed that consanguinity has a detrimental effect on many aspects of reproductive health.

Modification of Minimum Moment Approach in Resource Leveling

Abstract: This paper proposes a modification to the minimum moment approach that is used for resource leveling as presented by Harris and based upon the critical path method. The proposed and the traditional methods were developed with the assumption of no activity splitting and a fixed project duration with unlimited availability of resources. The difference between these methods is in the criteria of selecting the activity that has to be shifted from its original position to a better position. This is judged by the change in the statistical moment of the resource histogram before and after such movement. In the proposed method, and for the activities that lie at the same sequence step, the activity that is to be shifted first is selected based upon both the value of its free float (\iS) and the value of its resource rate (\iR). In this way, the calculation of the improvement factor is needed only to determine the extent to which an activity is to be shifted. On the other hand, using the traditional method, the activity with the maximum improvement factor found for each possible day of shifting is selected first. The process is then repeated for all remaining activities using the updated histogram resulting from the shifted activity. The proposed method significantly reduces the calculations so that the number of iterations in each sequence step is equal to the number of its noncritical activities (\in) as compared to (\in!) in the traditional method. In addition, the calculation process using the proposed method is easier—especially for manual computations—than the traditional one. The results were insignificantly different, and in many cases they were identical. In this paper, the traditional and the proposed methods will be presented along with an example problem that was solved using the two methods. It should be noted that neither of the two methods provides the true minimum moment.

Manufacturing parameters and quality characteristics of spray dried jameed

Abstract: Spray drying of jameed - a dried fermented dairy product, is investigated. The study covers the effects of the operating variables upon the physical and chemical characteristics of the dried product. The investigated variables were: feed total solids, feed flow rate, inlet air temperature, air flow rate and atomizer pressure. The product characteristics measured were: total solids, bulk density, average particle size, wettability, dipersibility, color, ash content, salt content, fat content and pH. Best overall results were obtained for a feed total solids of 17%, feed flow rate of 36.5 ml/min, inlet air temperature of 100 /C, air flow rate of 632 cm3/s, and atomizer pressure of 1.5 bar.

Redefining the water poverty index.

Abstract: The Water Poverty Index (WPI) of arid and semiarid climatic zones is redefined by introducing the contribution of rainfed agriculture into WPI calculations and by making the WPI equation account for diversities in climatic conditions within arid and semiarid zones and for recycled household water used in irrigation.

Fibroadenoma of the supernumerary breast of the axilla.

Abstract: Supernumerary breast or polymastia is a well documented anomaly of the breast, and commonly presents along the embryonic milk line extending between the axilla and groin. However, cases of polymastia have been recorded in the face, vulva and perineum. The clinical significances of these anomalies include their susceptibility to inflammatory and malignant changes, and their association with other congenital anomalies of the urinary and cardiovascular systems. The present article reports a case of fibroadenoma developing in the supernumerary breast of the right axilla in a 28 year old woman. Clinical and mammography examination of both breasts revealed no abnormalities and no lymph nodes were detected in the axillae or the neck. No associated urologic or cardiovascular abnormalities were found, and the histopathological examination of the excisional biopsy samples showed a well-defined, capsulated intracanalicular type of fibroadenoma similar to that of eutopic mammary tissue. The article also outlines the common congenital anomalies of the breast, and emphasizes on their proper clinical assessment for any other associated anomaly together with adequate surgical excision and regular follow up of the treated patients.

Prediction intervals for the future record values from exponential distribution: comparative study

Abstract: !n this paper we consider the predicf an problem of the future nth record value based an the first m (m < n) observed record values from one-parameter exponential distribution. We introduce four procedures for obtaining prediction intervals for the nth record value. The performance of the so obtained intervals is assessed through numerical and simulation studies. In these studies, we provide the means and standard errors of lower limits. upper limits and lengths of prediction intervals. Further, we check the validation of these intervals based on some point predictors.