Showing papers by "University of Jordan published in 2013"

Green synthesis of silver nanoparticles using carob leaf extract and its antibacterial activity

Abstract: Background This paper describes a rapid and eco-friendly method for green synthesis of silver nanoparticles from aqueous solution of silver nitrate using carob leaf extract (Ceratonia siliqua) in a single-pot process.

Effect of rainfall intensity, slope, land use and antecedent soil moisture on soil erosion in an arid environment

Abstract: Most climate change scenarios predict a significant increase in the frequency of high intensity rainfall events especially in the dry areas, which will increase runoff and soil erosion. Understanding the factors that control soil erosion is crucial to recommending appropriate measures to protect soils and reduce their vulnerability. The objective of this research was to investigate the effect of rainfall intensity, slope, land use and antecedent soil moisture on soil erosion and runoff. Twelve sites from Al-Muwaqqar watershed, Jordan, were selected to represent six slope angles: 1, 2, 3, 5, 7 and 9%. Two sites, one cultivated with barley and one as rangeland, were selected within each slope. Erosion was measured under three rainfall intensities: 3, 5 and 10 mm h−1; and three different antecedent soil moisture contents: dry, wet and very wet; using a rotating disk rainfall simulator. Regression equations indicated that rainfall intensity was the most important factor affecting soil erosion and that erosion could occur at a relatively small intensity on wet soils as a result of subsequent rainfall events. Soil erosion on cultivated land was primarily affected by moisture content, while on uncultivated land, it was mostly affected by slope steepness. Rainfall intensity, slope and antecedent moisture explained 84–89 and 59–66% of the variation in runoff and soil loss, respectively. The results indicated the significant influence of cultivating the land on soil erosion. Copyright © 2013 John Wiley & Sons, Ltd.

Why people keep coming back to Facebook: Explaining and predicting continuance participation from an extended theory of planned behaviour perspective

Abstract: This study examines the continuance participation intentions and behaviour on Facebook, as a representative of Social Networking Sites (SNSs), from a social and behavioural perspective. The study extends the Theory of Planned Behaviour (TPB) through the inclusion of perceived value construct and utilizes the extended theory to explain users' continuance participation intentions and behaviour on Facebook. Despite the recent massive uptake of Facebook, our review of the related-literature revealed that very few studies tackled such technologies from the context of post-adoption as in this research. Using data from surveys of undergraduate and postgraduate students in Jordan (n=403), the extended theory was tested using statistical analysis methods. The results show that attitude, subjective norm, perceived behavioural control, and perceived value have significant effect on the continuance participation intention of post-adopters. Further, the results show that continuance participation intention and perceived value have significant effect on continuance participation behaviour. However, the results show that perceived behavioural control has no significant effect on continuance participation behaviour of post-adopters. When comparing the extended theory developed in this study with the standard TPB, it was found that the inclusion of the perceived value construct in the extended theory is fruitful; as such an extension explained an additional 11.6% of the variance in continuance participation intention and 4.5% of the variance in continuance participation behaviour over the standard TPB constructs. Consistent with the research on value-driven post-adoption behaviour, these findings suggest that continuance intentions and behaviour of users of Facebook are likely to be greater when they perceive the behaviour to be associated with significant added-value (i.e. benefits outperform sacrifices).

Nanoparticle-protein interactions: a thermodynamic and kinetic study of the adsorption of bovine serum albumin to gold nanoparticle surfaces.

Abstract: Investigating the adsorption process of proteins on nanoparticle surfaces is essential to understand how to control the biological interactions of functionalized nanoparticles. In this work, a library of spherical and rod-shaped gold nanoparticles (GNPs) was used to evaluate the process of protein adsorption to their surfaces. The binding of a model protein (bovine serum albumin, BSA) to GNPs as a function of particle shape, size, and surface charge was investigated. Two independent comparative analytical methods were used to evaluate the adsorption process: steady-state fluorescence quenching titration and affinity capillary electrophoresis (ACE). Although under favorable electrostatic conditions kinetic analysis showed a faster adsorption of BSA to the surface of cationic GNPs, equilibrium binding constant determinations indicated that BSA has a comparable binding affinity to all of the GNPs tested, regardless of surface charge. BSA was even found to adsorb strongly to GNPs with a pegylated/neutral surf...

A study of the optical bandgap energy and Urbach tail of spray-deposited CdS:In thin films

Abstract: Cadmium sulfide (CdS) is an interesting material for applications in optoelectronic and pho- tovoltaic devices. In particular, thin films of n-type CdS are widely used as a window layer in heterojunction solar cells. The optical bandgap energy is the most interesting parameter for these applications. For spray-deposited indium-doped cadmium sulfide (CdS:In) thin films prepared on glass substrates the transmittance measurements were used to estimate the optical bandgap energy. Tailing in the bandgap was observed and found to obey Urbach rule. The effects of film thickness and the substrate temperature on the bandgap energy and the width of the tail were investigated. A linear relation between bandgap energy and width of the tail was found.

Inverse Rate-Dependent Prandtl–Ishlinskii Model for Feedforward Compensation of Hysteresis in a Piezomicropositioning Actuator

Abstract: Piezomicropositioning actuators, which are widely used in micropositioning applications, exhibit strong rate-dependent hysteresis nonlinearities that affect the accuracy of these micropositioning systems when used in open-loop control systems, and may also even lead to system instability of closed-loop control systems. Feedback control techniques could compensate for the rate-dependent hysteresis in piezomicropositioning actuators. However, accurate sensors over a wide range of excitation frequencies and the feedback control techniques inserted in the closed-loop control systems may limit the use of the piezomicropositioning and nanopositioning systems in different micropositioning and nanopositioning applications. We show that open-loop control techniques, also called feedforward techniques, can compensate for rate-dependent hysteresis nonlinearities over different excitation frequencies. An inverse rate-dependent Prandtl-Ishlinskii model is utilized for feedforward compensation of the rate-dependent hysteresis nonlinearities in a piezomicropositioning stage. The exact inversion of the rate-dependent model holds under the condition that the distances between the thresholds do not decrease in time. The inverse of the rate-dependent model is applied as a feedforward compensator to compensate for the rate-dependent hysteresis nonlinearities of a piezomicropositioning actuator at a range of different excitation frequencies between 0.05-100 Hz. The results show that the inverse compensator suppresses the rate-dependent hysteresis nonlinearities, and the maximum positioning error in the output displacement at different excitation frequencies.

New Results on Fractional Power Series: Theory and Applications

Abstract: In this paper, some theorems of the classical power series are generalized for the fractional power series. Some of these theorems are constructed by using Caputo fractional derivatives. Under some constraints, we proved that the Caputo fractional derivative can be expressed in terms of the ordinary derivative. A new construction of the generalized Taylor’s power series is obtained. Some applications including approximation of fractional derivatives and integrals of functions and solutions of linear and nonlinear fractional differential equations are also given. In the nonlinear case, the new and simple technique is used to find out the recurrence relation that determines the coefficients of the fractional power series.

Strategic Closed-Loop Facility Location Problem With Carbon Market Trading

Abstract: The burgeoning environmental regulations are forcing companies to green their supply chains by integrating all of their business value-adding operations so as to minimize the impact on the environment. One dimension of greening the supply chain is extending the forward supply chain to collection and recovery of products in a closed-loop configuration. Remanufacturing is the basis of profit-oriented reverse logistics in which recovered products are restored to a marketable condition in order to be resold to the primary or secondary market. In this paper, we introduce a multiechelon multicommodity facility location problem with a trading price of carbon emissions and a cost of procurement. The company might either incur costs if the carbon cap, normally assigned by regulatory agencies, is lower than the total emissions, or gain profit if the carbon cap is higher than the total emissions. A numerical study is presented which studies the impact of different carbon prices on cost and configuration of supply chains.

Autophagy restricts Chlamydia trachomatis growth in human macrophages via IFNG-inducible guanylate binding proteins

Abstract: Interferon γ (IFNG) is a key host response regulator of intracellular pathogen replication, including that of Chlamydia spp The antichlamydial functions of IFNG manifest in a strictly host, cell-type and chlamydial strain dependent manner. It has been recently shown that the IFNG-inducible family of immunity-related GTPases (IRG) proteins plays a key role in the defense against nonhost adapted chlamydia strains in murine epithelial cells. In humans, IFN-inducible guanylate binding proteins (hGBPs) have been shown to potentiate the antichlamydial effect of IFNG; however, how hGBPs regulate this property of IFNG is unknown. In this study, we identified hGBP1/2 as important resistance factors against C. trachomatis infection in IFNG-stimulated human macrophages. Exogenous IFNG reduced chlamydial infectivity by 50 percent in wild-type cells, whereas shRNA hGBP1/2 knockdown macrophages fully supported chlamydial growth in the presence of exogenous IFNG. hGBP1/2 were recruited to bacterial inclusions in human macrophages upon stimulation with IFNG, which triggered rerouting of the typically nonfusogenic bacterial inclusions for lysosomal degradation. Inhibition of lysosomal activity and autophagy impaired the IFNG-mediated elimination of inclusions. Thus, hGBP1/2 are critical effectors of antichlamydial IFNG responses in human macrophages. Through their capacity to remodel classically nonfusogenic chlamydial inclusions and stimulate fusion with autophagosomes, hGBP1/2 disable a major chlamydial virulence mechanism and contribute to IFNG-mediated pathogen clearance.

The relations of Arab Jordanian adolescents' perceived maternal parenting to teacher-rated adjustment and problems: the intervening role of perceived need satisfaction.

Abstract: Although the effects of important parenting dimensions, such as responsiveness and psychological control, are well documented among Western populations, research has only recently begun to systematically identify psychological processes that may account for the cross-cultural generalization of these effects. A first aim of this study was to examine whether perceived maternal responsiveness and psychological control would relate differentially to teacher ratings of adolescent adjustment in a vertical-collectivist society (i.e., Jordan). The most important aim of this study was to examine, on the basis of self-determination theory, whether these associations would be accounted for by perceived satisfaction of the basic psychological needs for autonomy, competence, and relatedness. Results in a large sample of Jordanian adolescents (N = 545) showed that perceived maternal psychological control and responsiveness yielded, respectively, a positive and negative association with teacher-rated problems, whereas psychological control was negatively related to teacher-rated adjustment. Further, these 2 parenting dimensions related to adjustment and problems via perceived satisfaction of the basic psychological needs for autonomy and competence (but not relatedness). The findings are discussed in light of the ongoing debate between universalistic and relativistic perspectives on parenting and adolescent adjustment.

Adaptation and translation of mental health interventions in Middle Eastern Arab countries: A systematic review of barriers to and strategies for effective treatment implementation:

Abstract: Aim:All too often, efficacious psychosocial evidence-based interventions fail when adapted from one culture to another. International translation requires a deep understanding of the local culture, nuanced differences within a culture, established service practices, and knowledge of obstacles and promoters to treatment implementation. This research investigated the following objectives to better facilitate cultural adaptation and translation of psychosocial and mental health treatments in Arab countries: (1) identify barriers or obstacles; (2) identify promoting strategies; and (3) provide clinical and research recommendations.Methods:This systematic review of 22 psychosocial or mental health studies in Middle East Arab countries identified more barriers (68%) than promoters (32%) to effective translation and adaptation of empirically supported psychosocial interventions.Results:Identified barriers include obstacles related to acceptability of the intervention within the cultural context, community and sy...

Efficient Improvements on the BDND Filtering Algorithm for the Removal of High-Density Impulse Noise

Abstract: Switching median filters are known to outperform standard median filters in the removal of impulse noise due to their capability of filtering candidate noisy pixels and leaving other pixels intact. The boundary discriminative noise detection (BDND) is one powerful example in this class of filters. However, there are some issues related to the filtering step in the BDND algorithm that may degrade its performance. In this paper, we propose two modifications to the filtering step of the BDND algorithm to address these issues. Experimental evaluation shows the effectiveness of the proposed modifications in producing sharper images than the BDND algorithm.

Deletions in GRID2 lead to a recessive syndrome of cerebellar ataxia and tonic upgaze in humans.

Abstract: Objective: To identify the genetic cause of a syndrome causing cerebellar ataxia and eye movement abnormalities. Methods: We identified 2 families with cerebellar ataxia, eye movement abnormalities, and global developmental delay. We performed genetic analyses including single nucleotide polymorphism genotyping, linkage analysis, array comparative genomic hybridization, quantitative PCR, and Sanger sequencing. We obtained eye movement recordings of mutant mice deficient for the ortholog of the identified candidate gene, and performed immunohistochemistry using human and mouse brain specimens. Results: All affected individuals had ataxia, eye movement abnormalities, most notably tonic upgaze, and delayed speech and cognitive development. Homozygosity mapping identified the disease locus on chromosome 4q. Within this region, a homozygous deletion of GRID2 exon 4 in the index family and compound heterozygous deletions involving GRID2 exon 2 in the second family were identified. Grid2-deficient mice showed larger spontaneous and random eye movements compared to wild-type mice. In developing mouse and human cerebella, GRID2 localized to the Purkinje cell dendritic spines. Brain MRI in 2 affected children showed progressive cerebellar atrophy, which was more severe than that of Grid2-deficient mice. Conclusions: Biallelic deletions of GRID2 lead to a syndrome of cerebellar ataxia and tonic upgaze in humans. The phenotypic resemblance and similarity in protein expression pattern between humans and mice suggest a conserved role for GRID2 in the synapse organization between parallel fibers and Purkinje cells. However, the progressive and severe cerebellar atrophy seen in the affected individuals could indicate an evolutionarily unique role for GRID2 in the human

Impact of Climate and Land Use Changes on Water and Food Security in Jordan: Implications for Transcending “The Tragedy of the Commons”

Abstract: This study investigates the impact of climate change and land use change on water resources and food security in Jordan. The country is dominated by arid climate with limited arable land and water resources, where the per capita share of water is less than 145 m3/year. The study focused on crop production and water resources under trends of anticipated climate change and population growth in the country. Remote sensing data were used to determine land use/cover changes and rates of urbanization, which took place at the cost of the cultivable land. Recession of irrigated areas led to lesser food production and food security. Outputs from crop production and water requirements models, in addition to regression analysis, were used to estimate the projected increase in agricultural water demand under the scenarios of increased air temperature and reduced rainfall by the years 2030 and 2050. Results indicated that problems of water scarcity and food insecurity would be exacerbated by climate change and increased population growth. To move from the tragedy of the commons towards transcendence, the study emphasized the need for adaptive measures to reduce the impacts of climate change on water resources and food security. The challenge, however, would remain the development and the efficient use of new water resources as a means for future sustainable development.

Confirmation of disordered structure of ultrasmall CdSe nanoparticles from X-ray atomic pair distribution function analysis

Abstract: The atomic pair distribution function (PDF) analysis of X-ray powder diffraction data has been used to study the structure of small and ultra-small CdSe nanoparticles. A method is described that uses a wurtzite and zinc-blende mixed phase model to account for stacking faults in CdSe particles. The mixed-phase model successfully describes the structure of nanoparticles larger than 2 nm yielding a stacking fault density of about 30%. However, for ultrasmall nanoparticles smaller than 2 nm, the models cannot fit the experimental PDF showing that the structure is significantly modified from that of larger particles and the bulk. The observation of a significant change in the average structure at ultra-small size is likely to explain the unusual properties of the ultrasmall particles such as their white light emitting ability.

FAM20A mutations can cause enamel-renal syndrome (ERS).

Abstract: Enamel-renal syndrome (ERS) is an autosomal recessive disorder characterized by severe enamel hypoplasia, failed tooth eruption, intrapulpal calcifications, enlarged gingiva, and nephrocalcinosis. Recently, mutations in FAM20A were reported to cause amelogenesis imperfecta and gingival fibromatosis syndrome (AIGFS), which closely resembles ERS except for the renal calcifications. We characterized three families with AIGFS and identified, in each case, recessive FAM20A mutations: family 1 (c.992G>A; g.63853G>A; p.Gly331Asp), family 2 (c.720-2A>G; g.62232A>G; p.Gln241_Arg271del), and family 3 (c.406C>T; g.50213C>T; p.Arg136* and c.1432C>T; g.68284C>T; p.Arg478*). Significantly, a kidney ultrasound of the family 2 proband revealed nephrocalcinosis, revising the diagnosis from AIGFS to ERS. By characterizing teeth extracted from the family 3 proband, we demonstrated that FAM20A−/− molars lacked true enamel, showed extensive crown and root resorption, hypercementosis, and partial replacement of resorbed mineral with bone or coalesced mineral spheres. Supported by the observation of severe ectopic calcifications in the kidneys of Fam20a null mice, we conclude that FAM20A, which has a kinase homology domain and localizes to the Golgi, is a putative Golgi kinase that plays a significant role in the regulation of biomineralization processes, and that mutations in FAM20A cause both AIGFS and ERS.

The state of hepatitis B and C in the Mediterranean and Balkan countries: report from a summit conference.

Abstract: The burden of disease due to chronic viral hepatitis constitutes a global threat. In many Balkan and Mediterranean countries, the disease burden due to viral hepatitis remains largely unrecognized, including in high-risk groups and migrants, because of a lack of reliable epidemiological data, suggesting the need for better and targeted surveillance for public health gains. In many countries, the burden of chronic liver disease due to hepatitis B and C is increasing due to ageing of unvaccinated populations and migration, and a probable increase in drug injecting. Targeted vaccination strategies for hepatitis B virus (HBV) among risk groups and harm reduction interventions at adequate scale and coverage for injecting drug users are needed. Transmission of HBV and hepatitis C virus (HCV) in healthcare settings and a higher prevalence of HBV and HCV among recipients of blood and blood products in the Balkan and North African countries highlight the need to implement and monitor universal precautions in these settings and use voluntary, nonremunerated, repeat donors. Progress in drug discovery has improved outcomes of treatment for both HBV and HCV, although access is limited by the high costs of these drugs and resources available for health care. Egypt, with the highest burden of hepatitis C in the world, provides treatment through its National Control Strategy. Addressing the burden of viral hepatitis in the Balkan and Mediterranean regions will require national commitments in the form of strategic plans, financial and human resources, normative guidance and technical support from regional agencies and research.

Factors Influencing Citizen Adoption of E-Government in Developing Countries: The Case of Jordan

Abstract: The main purposes of this study are to investigate citizen adoption of e-government services in Jordan and to explore factors affecting the level of adoption of e-government services. Importantly, this study aims to develop a conceptual framework that is based on previous literature of Technology Acceptance Model TAM in order to examine the relationships between certain factors government trustworthiness, service quality and citizen satisfaction and citizen adoption of e-government services. A self-administered questionnaire was used to capture data from 356 Jordanian citizens across the country randomly. The findings indicate that perceived usefulness, perceived ease of use, citizen satisfaction and trustworthiness are significant predictors of the Jordanian intention to use an e-government service. The results also showed that the service quality dimensions: responsiveness, reliability, and empathy have significant impacts on the citizen satisfaction. The study has made significant contributions to the body of knowledge at academic and practical levels as an important exploratory study that was conducted in the context of Jordan, a developing country with genuine need for more research works on e-government issues. In addition, this study provides some valuable insights into the performance and adoption of e-government in Jordan that could help government agencies to improve the effectiveness of their services.