Electron refraction at lateral atomic interfaces

We present theoretical simulations of electron refraction at the lateral atomic interface between a “homogeneous” Cu(111) surface and the “nanostructured” one-monolayer (ML) Ag/Cu(111) dislocation lattice. Calculations are performed for electron binding energies barely below the 1 ML Ag/ Cu(111) M-point gap (binding energy EB ¼53 meV, below the Fermi level) and slightly above its C -point energy (EB ¼160 meV), both characterized by isotropic/circular constant energy surfaces. Using plane-wave-expansion and boundary-element methods, we show that electron refraction occurs at the interface, the Snell law is obeyed, and a total internal reflection occurs beyond the critical angle. Additionally, a weak negative refraction is observed for EB ¼53 meV electron energy at beam incidence higher than the critical angle. Such an interesting observation stems from the interface phase-matching and momentum conservation with the umklapp bands at the second Brillouin zone of the dislocation lattice. The present analysis is not restricted to our Cu-Ag/Cu model system but can be readily extended to technologically relevant interfaces with spinpolarized, highly featured, and anisotropic constant energy contours, such as those characteristic for Rashba systems and topological insulators. Published by AIP Publishing.Peer ReviewedPostprint (published version

Theory of reactions between hydrogen and group-III acceptors in silicon

The thermodynamics of several reactions involving atomic and molecular hydrogen with group-III acceptors is investigated. The results provide a first-principles-level account of thermally- and carrier-activated processes involving these species. Acceptor-hydrogen pairing is revisited as well. We present a refined physicochemical picture of long-range migration, compensation effects, and short-range reactions, leading to fully passivated $\equiv\textrm{Si-H}\cdots X\equiv$ structures, where $X$ is a group-III acceptor element. The formation and dissociation of acceptor-H and acceptor-H$_{2}$ complexes is considered in the context of Light and elevated Temperature Induced Degradation (LeTID) of silicon-based solar cells. Besides explaining observed trends and answering several fundamental questions regarding the properties of acceptor-hydrogen pairing, we find that the BH$_{2}$ complex is a by-product along the reaction of H$_{2}$ molecules with boron toward the formation of BH pairs (along with subtraction of free holes). The calculated changes in Helmholtz free energies upon the considered defect reactions, as well as activation barriers for BH$_{2}$ formation/dissociation (close to $\sim1$ eV) are compatible with the experimentally determined activation energies of degradation/recovery rates of Si:B-based cells during LeTID. Dihydrogenated acceptors heavier than boron are anticipated to be effective-mass-like shallow donors, and therefore, unlikely to show similar non-radiative recombination activity

Mitigation Measures for Gaza Coastal Erosion

Coastal erosion is an ongoing hazard affecting Gaza beach, but is worsening due to a wide range of human activities such as the construction of Gaza fishing harbor in 1994-1998. The net annual alongshore sediment transport is about 190×103 m3, but can vary significantly depending on the severity of winter storms. According to the observed wave heights and directions, the net waves are cross-shore, therefore vast quantities of sediments may transfer to deep sea. The main objective of this study is to mitigate the erosion problem of Gaza coast. Change detection analysis was used to compute the spatial and temporal change of Gaza shoreline between 1972 and 2010. The results show negative rates in general, which means that the erosion was the predominant process. Gaza fishing harbor caused a serious damage to the Beach Camp shoreline. Consequently, several mitigation measures were considered in this study, which are: relocation of Gaza fishing harbor to offshore, groins, detached breakwaters, wide-crested submerged breakwaters and beach nourishment. Several numerical model tests associated with coastal structures are conducted to investigate the influence on morphodynamics. The results show that the relocation of the harbor is the best alternative to stop trapping of the sediments. If for any reason the relocation was not carried out, the wide-crested submerged breakwater alternative is an effective structure for preventing sandy beach erosion. The artificial reef type of submerged breakwaters with beach nourishment is recommended for Gaza beach, because it is an environmentally friendly and improving the ecosystem of marine life

Prevalence and predictive factors associated with stunting in preschool children in a governorate of Iraq: a community-based cross-sectional study

IntroductionThe prevalence and risk factors of stunting in various geographical regions have been well investigated. However, not enough data exists regarding the communities in Iraq. This study investigated the prevalence and risk factors of stunting in preschool children in Halabja governorate.MethodsThe required data for the study was collected through a structured questionnaire form from the children’s parents. Then, the height and weight of the children were measured. According to the World Health Organization Child Growth Standards and using the WHO Anthro Survey Analyser software, children were classified as “stunted” when their height-for-age z-score was below two standard deviations.ResultsA total of 646 children were included, of which 310 (48%) were male and 336 (52%) were female. The gestational age of 556 (86%) children was 9 months, while 84 (13%) were born between 7–9 months, and 6 (1%) were born in 7 months. Regarding feeding during the first 2 years of life, 229 children (35.4%) were exclusively breastfed, 93 (14.4%) were bottle-fed, and 324 (50.2%) had mixed feeding. The prevalence of stunting was 7.9% in the sample pool, with 4.6% of females and 3.3% of males. Among stunted children, 6.35% were term babies, and 1.55% were preterm babies. None of the studied factors had a significant association with stunting.ConclusionThe prevalence of stunting in the studied population was 7.9%. However, we could not find any significant association between the studied factors and stunting. Thus, the factors that may significantly affect stunting in our area of study, especially the historical chemical warfare side effects, need to be more extensively investigated in future studies

To fuse or not to fuse : the elderly patient with lumbar stenosis and low-grade spondylolisthesis. Systematic review and meta-analysis of randomised controlled trials

Open Access via the Elsevier R&P Agreement Acknowledgements AA: primary reviewer, literature review, data-analysis and drafting manuscript. FB: literature review, data-analysis and drafting manuscript. LB: critical appraisal, drafting manuscript. JF: critical appraisal, drafting manuscript. CM: critical appraisal, drafting manuscript. MR: literature review, data-analysis and drafting manuscript. IC: second reviewer, drafting manuscript. TS: supervision, critical revision. SB: supervision, senior reviewer for systematic review, critical revision. PKM: supervision, senior reviewer for systematic review, critical revision. PKM is the guarantor.Peer reviewedPublisher PD

EXPERIMENTAL OBSERVATIONS ON THE BEHAVIOR OF A PILED RAFT FOUNDATION

The piled raft is a geotechnical composite construction consisting of three elements: piles, raft and soil. In the design of piled rafts, the load shared between the piles and the raft, and the piles are used up to a load level that can be of the same order of magnitude as the bearing capacity of a comparable single pile or even greater. Therefore, the piled raft foundation allows reduction of settlements in a very economic way as compared to traditional foundation concepts. This paper presents experimental study to investigate the behavior of piled raft system in sandy soil. A small scale “prototype” model was tested in a sand box with load applied to the system through a compression machine. The settlement was measured at the center of the raft, strain gages were used to measure the strains and calculate the total load carried by piles. Four configurations of piles (2x1, 3x1, 2x2 and 3x2) were tested in the laboratory, in addition to rafts with different sizes. The effects of pile length, pile diameter, and raft thickness on the load carrying capacity of the piled raft system are included in the load-settlement presentation. It was found that the percentage of the load carried by piles to the total applied load of the groups (2x1, 3x1, 2x2, 3x2) with raft thickness of 5 mm, pile diameter of 9 mm, and pile length of 200 mm was 28% , 38% , 56% , 79% , respectively. The percent of the load carried by piles increases with the increase of number of piles

Production of Function yogurts drink fortified with different types of herbal extracts and study its biological attributes in hepatitis rats

The present study aimed to produce function yoghurt drink fortified with different types of herbal extracts (Ginger, Amla, Curcuma) and assess its therapeutic effect in hepatitis rats. The rats were randomly divided into two main groups. The first group were control (-) (6 rats) was fed on a standard diet, while the second group (30 rats) were fed on standard diet and injected it by CCl4 "for two weeks" to induce chronic damage in the liver (hepatitis) then divided into five groups (6 rats each group), then treated by plain drinking yoghurt and different herbal drinking yoghurt fortified with different types of herbs extract. Different Biological attributes were determined. The antioxidant activity, total phenolic content and chemical properties were evaluated in herbal extracts and yoghurt product and their hepatoprotective effect of each alone evaluated in albino rats against carbon tetrachloride (CCL4) induced liver injury. The hepatoprotective activity was assessed using various biochemical parameters and histopathological studies. The results indicated that functional flavoured drinking yoghurt containing herbal extract exhibited no significant differences were observed in total solids, fat, protein, ash, and lactose content them control samples. Drinking yoghurt fortified with Curcuma exhibited highest content of antioxidant activity and total phenolic content among all treatments. Also, rats fed on diet supplemented with drinking yoghurt fortified with Curcuma for 28 days showed higher potential hepatoprotective effects compared to liver injury control group (IC). The rats succeeded to restore the biochemical parameters and improved the histological alteration of the liver. This improvement was pronounced partly in the group received drinking yoghurt fortified with Ginger and Amla herbal extracts while, the group received drinking yoghurt fortified with Curcuma herbal extract were improved totally. It could be concluded that drinking yoghurt fortified with different herbal extract especially Curcuma can be used as ingredients in functional foods for people suffering from liver diseases

Impacts of the Cairo Metro

The Cairo Metro the first in Africa and the Middle East is a two-line system, heavily-used. Data from the operator and a direct passenger survey are used to illustrate patterns of use and draw policy implications for other systems. While current revenue exceeds operating costs, cross-subsidies may exist between different passenger groups as a result of highly-discounted student season tickets. A fare increase in 1996 is used to estimate short-run elasticity of demand with respect to price, approximately 0.2, a similar figure to other metro systems. Substantial use is made of motorised feeder modes, notably shared taxis (paratransit minibuses). The high level of use occurs despite a substantial premium over other public transport fares, and lack of integrated ticketing. A likely explanation is that the fares are reasonable compared with incomes, and that the price differential is offset for many users by the time savings vis a vis congested traffic conditions.Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne