Plasmonic waveguides and nano-antennas for optical communications

The field of plasmonics has received great attention during the past years. Plasmonic devices are characterized by their small electrical size which enabled researchers to overcome the challenge of the size mismatch between the bulky photonic devices and the small electronic circuits. Plasmonic metals are characterized by their lossy dielectric nature which is different from the highly conductive classical metals. Consequently, the design of plasmonic devices necessitates upgrading the existing solvers to take into consideration their material properties at the optical frequency range. In this thesis, a plasmonic transmission line mode solver is developed in which the propagation characteristics of plasmonic transmission lines/waveguides are calculated. More specifically, the solver calculates the propagation constant, losses, and mode profile(s) of the propagating mode(s). The transmission lines can have any topology and are assumed to be placed within a stack of flat layers. The solver is developed using the Method of Moments technique which is characterized by its tremendously decreased number of unknowns compared to the finite element/difference methods leading to much faster calculation time. The solver is tested on several plasmonic transmission lines of various topologies, number of metallic strips and/or surrounding media. These transmission lines include rectangular strip, circular strip, triangular strip, U-shaped strip, horizontally coupled strips, and vertically coupled strips. The obtained results are compared with those calculated by the commercial tool “CSTâ€. Very good agreement between both solvers is achieved. The second line presented within this thesis is concerned with the design of plasmonic wire-grid nano-antenna arrays. The basic element of this array is a nano-rod, whose propagation characteristics are first obtained using the developed solver. The arrays are then optimized using “CSTâ€. Within the context of this thesis, three nano-antenna arrays are proposed: a five-element wire-grid array, an eleven-element wire-grid array, and a novel circularly polarized wire-grid array. All of these arrays have high directivity and are suitable for inter-/intra-chip optical communication, where they replace the losing transmission lines

Does Volatility Generate Major and Minor Stocks in Saudi Stocks Market?

This study attempts to answer the main question: are there reciprocal effects between the variances of the stock returns in the Saudi market, also the answer to a sub-question. What are the leading stocks in the Saudi market?. Study selected a sample of five stocks representing the basic materials, banking, services, food and transport sectors (SABIC, Al Rajhi, Etisalat, Almarai and Al Bahri respectively). The data sample for the period from 2011 to 2016 is taken, which represents the lifespan of the five-year plan. Daily stock returns were calculated during this period. Study applies the M GARCH-VEC methodology to estimate stock return variances and then perform a multiple regression of five equations using the ARCH Heteroscedasticity estimator. Results of the analysis show a positive effect between stock return variances as well as a positive automatic variance of all stocks returns variances. Finally, the results of the regression analysis of the various equations show that the returns variances of SABIC and Al Rajhi stocks have a dominant impact on the rest of the stock's returns. So they are considered as leading stocks in the market. While the variances returns of Etisalat, Almarai and Al Bahri have a limited impact on the rest of the stocks variances returns, so they are considered as minor stock

An Improved Binary Grey-Wolf Optimizer with Simulated Annealing for Feature Selection

This paper proposes improvements to the binary grey-wolf optimizer (BGWO) to solve the feature selection (FS) problem associated with high data dimensionality, irrelevant, noisy, and redundant data that will then allow machine learning algorithms to attain better classification/clustering accuracy in less training time. We propose three variants of BGWO in addition to the standard variant, applying different transfer functions to tackle the FS problem. Because BGWO generates continuous values and FS needs discrete values, a number of V-shaped, S-shaped, and U-shaped transfer functions were investigated for incorporation with BGWO to convert their continuous values to binary. After investigation, we note that the performance of BGWO is affected by the selection of the transfer function. Then, in the first variant, we look to reduce the local minima problem by integrating an exploration capability to update the position of the grey wolf randomly within the search space with a certain probability; this variant was abbreviated as IBGWO. Consequently, a novel mutation strategy is proposed to select a number of the worst grey wolves in the population which are updated toward the best solution and randomly within the search space based on a certain probability to determine if the update is either toward the best or randomly. The number of the worst grey wolf selected by this strategy is linearly increased with the iteration. Finally, this strategy is combined with IBGWO to produce the second variant of BGWO that was abbreviated as LIBGWO. In the last variant, simulated annealing (SA) was integrated with LIBGWO to search around the best-so-far solution at the end of each iteration in order to identify better solutions. The performance of the proposed variants was validated on 32 datasets taken from the UCI repository and compared with six wrapper feature selection methods. The experiments show the superiority of the proposed improved variants in producing better classification accuracy than the other selected wrapper feature selection algorithms

Two Levels of Palmitic Acid-Enriched Fat Supplement Affect Lactational Performance of Holstein Cows and Feed Utilization of Barki Sheep

The effect of feeding palmitic acid-enriched protected fat (PPF) supplement at two levels to increase energy density of diets was tested. In experiment 1, 21 multiparous lactating Holstein cows were fed on a basal diet without PPF supplementation (Control) or supplemented with 250 g (MG250) or 500 g PPF (MG500) for 13 weeks. In experiment 2, 12 adult Barki sheep were fed a basal diet without PAF supplementation (Control), or supplemented with 25 g (ME25), or 50 g of PPF (ME50 treatment) for 1 month. In experiment 1, MG250 treatment increased (

Two Levels of Palmitic Acid-Enriched Fat Supplement Affect Lactational Performance of Holstein Cows and Feed Utilization of Barki Sheep

The effect of feeding palmitic acid-enriched protected fat (PPF) supplement at two levels to increase energy density of diets was tested. In experiment 1, 21 multiparous lactating Holstein cows were fed on a basal diet without PPF supplementation (Control) or supplemented with 250 g (MG250) or 500 g PPF (MG500) for 13 weeks. In experiment 2, 12 adult Barki sheep were fed a basal diet without PAF supplementation (Control), or supplemented with 25 g (ME25), or 50 g of PPF (ME50 treatment) for 1 month. In experiment 1, MG250 treatment increased (

Assessment of Photodynamic Therapy and Nanoparticles Effects on Caries Models

AIM: To assess the antibacterial competence of 650 nm diode laser, Methylene Blue (MB) and Silver Nano-Particles (Ag NPs) on Streptococcus mutans in biofilm-induced caries models.MATERIAL AND METHODS: One hundred eighty specimens were prepared and equally divided into 6 groups. One group was untreated (control), and the others were subjected to either MB, laser, Ag NPs, the combination of MB and Laser or MB, laser and Ag NPs.RESULTS: Comparison of the log10 mean Colony Forming Units per millilitre (CFU/ml) values of each of the treated 5 groups and the control group was found statistically significant (P-value < 0.05).The combination of MB, laser and Ag NPs recorded the greatest reduction (95.28%). MB alone represented the least capable (74.09%). The efficiency differences among the Ag NPs treated group; the Laser treated group and the combined MB/Laser treated group were found statistically insignificant.CONCLUSION: The combination of MB, 650 nm diode laser and Ag NPs may be among the highly effective modern antimicrobial therapeutics in dentistry

Co-existence of a giant splenic hemangioma and multiple hepatic hemangiomas and the potential association with the use of oral contraceptives: a case report

<p>Abstract</p> <p>Introduction</p> <p>Hepatic and splenic hemangiomas are common benign tumors that mainly affect female patients. Giant splenic hemangiomas are extremely rare, especially when correlated with multiple hepatic hemangiomas. Pathogenetic mechanisms between hemangiomas and oral contraceptives, as well as therapeutic approaches, are analyzed in this case report, in particular for the management of synchronous splenic and hepatic hemangiomas.</p> <p>Case presentation</p> <p>We report here a 42-year-old woman with a giant splenic hemangioma, multiple hepatic hemangiomas and a history of oral estrogen intake for many years. At first it was difficult to determine the organ from which the giant hemangioma originated. Angiography proved extremely helpful in tracing its origin in the spleen. Hematomas in the giant hemangioma posed a significant threat of rupture and catastrophic hemorrhage. We left the small hepatic hemangiomas in place, and removed the spleen along with the giant splenic hemangioma.</p> <p>Conclusion</p> <p>Diagnostic pitfalls in the determination of the origin of this giant hemangioma, attribution of its origin to the spleen angiographically, the unusual co-existence of the giant splenic hemangioma with multiple hepatic ones, and the potential threat of rupture of the giant hemangioma are some of the highlights of this case report. Estrogen administration represents a pathogenic factor that has been associated with hemangiomas in solid organs of the abdominal cavity. The therapeutic dilemma between resection and embolization of giant hemangiomas is another point of discussion in this case report. Splenectomy for the giant splenic hemangioma eliminates the risk of rupture and malignant degeneration, whereas observation for the small hepatic ones (<4 cm) was the preferable therapeutic strategy in our patient.</p

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was USD 92 492 million using approach 1 and USD 73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was USD 95 004 million using approach 1 and USD 75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially.publishedVersio

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P &lt; 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely