Procjena učinkovitosti prospajanja komutatora

Discrete-time multiserver queues have been successfully used in the performance evaluation of computer and communication systems in various contexts such as TDM, voice-data integration, deflection routing and more recently, ATM-switching technology. In digital communication systems, buffers are used for the temporary storage of digital information awaiting transmission via some communication channel(s). Usually, information presents itself in the form of fixed-size packets, and synchronous (slotted) transmission is used so that the buffers can be modelled as discrete-time queuing systems. In this article, performance analysis of space division output buffered switches operating in an ATM multimedia environment is presented. Fixed size packets arrive onto the switch inputs in each time slot. The switch is modelled as a discrete-time, batch arrival, multiserver queuing system, with infinite buffer and geometric service times. The main contribution of this work is using multiserver case and geometric service time. Many performance measures such as System occupancy, Queuing time, Unfinished work and Waiting time are analysed. Probability Generating Functions (PGFs) and expectations for the corresponding random variables are derived. The results of the analysis have been verified in many ways. First, they have been used to generate the results of some previous analyses as special cases. Second, they obviously seem to preserve classical queuing relations (e.g. the famous Little\u27s formula). Last, they have been shown to generate intuitively acceptable graphs, when translated into numerical values.Diskretni višeserverski redovi uspješno su korišteni kod analize učinkovitosti računalnih i komunikacijskih sustava u različitim okolnostima poput TDM-a, glasovno-podatkovne integracije, ATM komutatora. U sustavima digitalnih komunikacija bufferi se koriste za privremeno pohranjivanje digitalnih informacija koje čekaju na prijenos preko komunikacijskih kanala. Uobičajeno se informacije prikazuju u formi paketa fiksne veličine, a sinkronizirani prijenos koristi se kako bi bufferi mogli biti modelirani kao diskretni sustav s čekanjem. U ovome članku prikazana je analiza učinkovitosti komutatora u ATM multimedijskom okruženju. Paketi fiksne veličine stižu na ulaze preklopnika u svakom vremenskom okviru. Preklopnik je modeliran kao diskretni višeserverski sustav s batch dolascima, s beskonačnim bufferom i geometrijskom razdiobom vremena servisa. Glavni doprinos ovog rada je korištenje višeserverskog slučaja i geometrijske razdiobe vremena servisa. Analizirane su mnoge mjere učinkovitosti kao što je zauzetost sustava, vrijeme čekanja, nezavršen posao. Izvedena je funkcija izvodnica i očekivanje za odgovarajuće slučajne varijable. Rezultati analize provjereni su na mnoge načine. Prvo su korišteni za generiranje rezultata nekih prethodnih analiza kao posebnih slučajeva. Zatim je utvrđeno da očito zadržavaju klasične relacije (npr. poznata Littlova formula). Konačno, pokazano je da generiraju intuitivno prihvatljive grafove kada se prenesu u numeričke vrijednosti

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

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Density functional theory and FTIR spectroscopic study of carboxyl group

911-917Both molecular modelling and FTIR have been used to study carboxyl group among acetic acid, potassium and sodium acetate, glycine, sodium salicylate, salicylic acid and cellulose acetate. Molecular modelling was used to study formic acid, carboxylic acids R-COOH, monovalent alkali carboxylate CH3COO-M, alanine, benzoic acid as well as naphthalene. Each structure was optimized using VWN/DZVP then vibrational spectra were further calculated at the same level of theory. The comparison between both calculated and experimental spectra showed good agreement with each other. Except for formic acid and free carboxyl, the characteristic band is shifted towards lower frequency

Comparison of Endothelial Cell Loss following the Big Bubble versus the Microbubble Incision Technique during Deep Anterior Lamellar Keratoplasty in Eyes with Keratoconus

Introduction. Deep anterior lamellar keratoplasty (DALK) is now becoming an increasingly popular surgical technique in treating corneal stromal pathologies with healthy endothelium. Several advantages of DALK over penetrating keratoplasty (PKP) have been described such as maintenance of globe integrity, absence of endothelial rejection, and a low rate of chronic endothelial cell loss (ECL). ECL following PKP results in 50% cell loss after 2 years from the estimated graft endothelial cell density (ECD). Although there are several reports confirming that ECL following DALK is similar to the physiologic cell loss 2 years after surgery, few reports discussed the surgically induced ECL due to difficulty in preoperative imaging of ECD. Materials and Methods. This prospective, interventional study included 20 eyes of 20 patients, who underwent DALK surgery. 11 eyes underwent DALK using the big bubble technique, while 9 eyes underwent the microbubble technique. Postoperative evaluation was done 3 months after surgery and included best spectacle corrected visual acuity (BSCVA), keratometric readings, and refraction measured using an autokeratorefractometer (Topcon KR800, Japan) and endothelial cell density (ECD) using noncontact specular microscopy (Nidek CEM-530, Japan). Results. Regarding postoperative parameters such as postoperative logMAR visual acuity, postoperative mean K, and postoperative K max, there was no statistical difference found between both groups (P=0.754, P=0.119, and P=0.970, respectively). Regarding change in specular endothelial cell density and percent change in the specular endothelial cell density, again there was no statistical difference between both groups with P=0.057 and P=0.126, respectively (significance defined as P<0.05). Conclusion. ECD is not affected by failure of the big bubble to form and continuing DALK via the microbubble technique

Graduation project 2018 Group G15

This paper aims to examine the uses and limitations of value added tax in Egypt The research uses the primary approach in collecting the required data through designing and distributing a questionnaire For a sample of tax officers in the Egyptian tax authority and tax experts from different public accounting firms in addition the research uses the quantitative approach in analyzing the collected data through applying SPSS software. The results of this study indicates that the agreement of all macro and micro uses of value added tax and the disagreement of macro and micro limitations of vat, so most of people saw that the benefits of value added tax in Egypt that vat is proportional tax and increases the level of export, minimizes tax evasion, improve the level of society fairness and stable source of government revenue in macro levelPresented To: DR: Tarek el-shazl

UV filters and high refractive index materials based on carboxymethyl cellulose sodium and CuO@ZnO core/shell nanoparticles

Abstract Nanoparticles have substantially contributed to the field of skincare products with ultraviolet (UV) filters to preserve human skin from sun damage. Thus, the current study aims to develop new polymer nanocomposites for the efficient block of UV light that results from the stratospheric ozone layer loss. Co-precipitation method was used to successfully synthesis CuO@ZnO core/shell NPs with a well-crystalline monoclinic CuO core and wurzite ZnO shell. Using the casting method, core/shell NPs were successfully introduced to carboxymethyl cellulose sodium (CMC). The CMC nanocomposites displayed considerably broader optical response extending from near-ultraviolet to visible light, which was likely due to heterojunction between the p-CuO core and n-ZnO shell and defects originating from the synthetic process. The transmittance of pure CMC in the UV, visible, and near IR regions is significantly reduced with the addition of 2 and 4 wt% of CuO@ZnO core/shell NPs to CMC. 99% of UV light is absorbed when 4 wt% of CuO@ZnO core/shell NPs are added. The addition of different concentrations of CMC nanocomposite to one of the sunblock in Egyptian market were studied and showing the highest Sun Protection Factor of 22. Moreover, optical dispersion parameters and refractive index were improved strongly with core/shell NPs addition

Structural and UV-blocking properties of carboxymethyl cellulose sodium/CuO nanocomposite films

Abstract Nanoparticles have made a substantial contribution to the field of skincare products with UV filters in preserving human skin from sun damage. The current study aims to create new polymer nanocomposite filters for the efficient block of UV light that results from the stratospheric ozone layer loss. The casting approach was used to add various mass fractions of copper oxide nanoparticles (CuO-NPs) to a solution of carboxymethyl cellulose (CMC). The amorphous nature of CMC was revealed by XRD analysis, with the intensity of the typical peak of virgin polymer in the nanocomposite spectrum decreasing dramatically as the doping amount was increased. The FTIR spectra revealed the functional groups of CMC and the good interaction between the CMC chain and CuO-NPs. Optical experiments revealed that the optical transmittance of pure CMC was over 80%, whereas it dropped to 1% when CuO-NPs content was increased to 8 wt.%. Surprisingly, the inclusion of CuO-NPs considerably improved the UV blocking property of the films extended from the UV region (both UV-A: 320–400 nm and UV-B: 280–320 nm) to the visible region. Optical band gap of CMC decreased sharply with increasing CuO concentration. The tunable optical characteristics can be utilized in UV- blocking filters and various optoelectronics applications

Epidemiology of urolithiasis with emphasis on ultrasound detection: A retrospective analysis of 5371 cases in Saudi Arabia

This retrospective study was conducted to determine the prevalence of urinary calculi in the indigenous population of Saudi Arabia and compare it with expatriates of different nationalities working in Saudi Arabia with emphasis on the anatomic location of the calculi and the role of ultrasound in the detection and management. The study included 5371 patients (both sexes, mean age 36.6 years) examined by us from September 2004 to February 2008. The patients hailed from 30 countries, which included Bangladesh (42.3%), Pakistan (18.3%), Yemen (17.5%), India (6.5%), Sudan (3.4%), Saudi Arabia (2.8%), Egypt (2.3%) and Eritrea (1.7%). All patients were referred for abdominal/renal ultrasonography. Urinary calculi were detected in 1029 patients. The distribution of calculi was as follows: Renal 73.3%, pelviureteric junction 2.3%, proximal, middle and distal thirds of the ureter 13%, vesicouretic junction 9.8%, vesical 1.1% and urethral 0.5%. The prevalence of urinary calculi according to ethnic origin in descending order of frequency was Egyptians (29.5%), Pakistani (24.9%), Indian (23.3%),Yemeni (20.5%), Sudanese (17.6%), Bangladeshi (16.2%), Eritrean (15.4%) and Saudi Arabian (7.4%). Urinary calculi were found in 19.1% of the studied population. Approximately three-quarters of the calculi were located within the kidney. The nationalities with the highest prevalences were Egyptian, Pakistani and Indian

Efficiently activated carbons from corn cob for methylene blue adsorption

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