Lumière lente par amplification paramétrique dans les fibres optiques biréfringentes

This thesis aims to the physical process of slow light induced by vector parametric amplification in highly and weakly birefringent optical fibers. Our first study concerns slow light induced by parametric amplification in highly birefringent fibers. Unlike the scalar process, we theoretically demonstrate that large optical delays can be in principle generated in birefringent fibers, one order of magnitude higher than for the scalar case. Both analytical and numerical results in the case of anomalous dispersion are presented. We further discuss the main limitations for slow light optical delays (signal pulse broadening, pump pulse depletion). The influence of the Raman gain is also studied both analytically and numerically. The second study focuses on slow light induced by parametric amplification in weakly birefringent fibers. We consider all possible configurations of polarization modulation instability, depending on the polarization axis of the pump pulse and on the dispersion regime, and we derive the slow-light optical delays. We clearly demonstrate that the configuration corresponding to a pump pulse polarized in the slow axis of the fiber and a signal pulse polarized on the fast axis, in the normal dispersion regime, gives the largest optical delays.Cette thèse a pour thème le processus physique de ralentissement de la lumière induit par amplification paramétrique vectorielle dans les fibres optiques biréfringentes. Notre première étude porte sur la lumière lente induite par amplification paramétrique vectorielle dans les fibres fortement biréfringentes. Contrairement au processus scalaire, nous montrons théoriquement que le processus vectoriel offre la possibilité de créer des bandes de gain paramétrique étroites et éloignées de la pompe, permettant de générer des retards optiques très importants, un ordre de grandeur supérieurs à ceux obtenus en amplification paramétrique scalaire. Des résultats analytiques et issus de simulations numériques dans le cas de dispersion normale ainsi que dans le cas de dispersion anormale sont présentés. Ensuite, nous discutons des principales limitations au retard optique (élargissement de l’impulsion pompe notamment) et nous étudions l’influence positive de l’effet Raman sur le retard optique. Notre seconde étude est consacrée à la lumière lente induite par amplification paramétrique dans les fibres faiblement biréfringentes. Nous traitons l’ensemble des configurations possibles d’instabilité de polarisation selon l’état initial de polarisation de l’impulsion pompe et du régime de dispersion. Nous démontrons clairement que la configuration correspondant à une impulsion pompe polarisée suivant l’axe lent de la fibre et une impulsion signal polarisée suivant l’axe rapide en régime de dispersion normale donne des retards optiques les plus importan

HUMAN RESOURCES MANAGEMENT PRACTICES AND EMPLOYEE ENGAGEMENT: KNOWN AND UNKNOWN ASPECTS IN THE LITERATURE

The relationship between Human Resources Management Practices (HRMP) and employee engagement has gained significant attention form scholars. Despite the importance of HRMP and its influence on employee engagement in the industry, little research has been done in terms of cultivating a systematic literature review in the subject area. Therefore, this paper aims to present a systematic literature review of articles based on forty highly ranked journals during the period of 1990 to 2017. The paper investigates the historical developments of Human Resources Management (HRM), HRMP, and employee engagement in order to present the conceptual evolvement and elaboration of the relationship between HRMP, and employee engagement. The literature highlighted that properly implementing HRMP influences employee engagement, and how this relationship positively affects the overall performance. In this term, a proposed framework is presented. Finally, the research limitations and avenues for future researchers are provided

Asymmetric Stark Shift in InAs/GaAsP(Q1.18) quantum dots grown on (311)B InP substrate

We present photocurrent (PC) spectroscopy of InAs/InGaAsP (Q1.18) quantum dots (QD) embedded in a PIN diode grown on InP(311)B substrate. From 300K and 77K spectra we deduce the transition energies for ground state of the dots. These energies are sensitive to applied bias and reveal an asymmetric quantum-confined Stark shift (QCSS) attributed to the presence of a strain-induced field in the dots

Effect of enamel thickness and dentin shade of resin composite on the final color reproduction.

Aim: To evaluate the effect of different dentin shades and different enamel shade thicknesses on the final color reproduction in class IV anterior resin composite restorations restored using the bilaminar technique. Materials and methods: 54 resin composite discs of 10mm diameter were prepared in this study. The discs were equally divided into 9 groups (n = 6) according to the two levels of the study, Level-1: Dentin shade (A1, A2 and A3) and Level-2: A3 enamel shade thickness (0.25mm, 0.5mm, 0.75mm). Each group had a 3mm-thick core layer of dentin shade either A1, A2 or A3 (ceram.x® duo, Dentsply Sirona, Germany) followed by the designated enamel shade thickness. Clinical spectrophotometer (VITA Easyshade® V, Germany) was used to measure the L*, a* and b* values of reference A1, A2 and A3 VITA classical shade tabs and resin composite discs. CIEDE2000 color difference formula (ΔE00) was adopted to calculate the color difference between the resin composite discs and their corresponding VITA classic shade tab. Data were analysed using two-way ANOVA followed by Tukey’s post hoc test. Comparison of main and simple effects were done utilizing one-way ANOVA followed by Tukey’s post hoc test. Results: Two-way ANOVA showed that the dentin shade and the enamel layer thickness as well as their interaction had a statistically significant effect on color difference (ΔE00) compared to the VITA classical reference tabs(p<0.001). Best shade matching to the control was obtained when A3 dentin shade was used with both 0.25mm and 0.75mm enamel thickness (3.13±0.48 and3.04±0.39, respectively) while least shade matching was obtained when A1 dentin shade was combined with 0.5mm enamel shade (6.07±0.41).  Conclusions:  When using the bilaminar technique in vertical anatomical layering of resin composite restorations, the thickness of the outer enamel composite together with the dentin shade used demonstrated a significant effect on the final shade.  The lighter the dentin shade used the thicker the enamel thickness needed for better shade reproduction and matching

Validation of plasma protein glycation and oxidation biomarkers for the diagnosis of autism

Autism Spectrum Disorder (ASD) is a common neurodevelopmental disorder in children. It is currently diagnosed by behaviour-based assessments made by observation and interview. In 2018 we reported a discovery study of a blood biomarker diagnostic test for ASD based on a combination of four plasma protein glycation and oxidation adducts. The test had 88% accuracy in children 5–12 years old. Herein, we present an international multicenter clinical validation study (N = 478) with application of similar biomarkers to a wider age range of 1.5–12 years old children. Three hundred and eleven children with ASD (247 male, 64 female; age 5.2 ± 3.0 years) and 167 children with typical development (94 male, 73 female; 4.9 ± 2.4 years) were recruited for this study at Sidra Medicine and Hamad Medical Corporation hospitals, Qatar, and Hospital Regional Universitario de Málaga, Spain. For subjects 5–12 years old, the diagnostic algorithm with features, advanced glycation endproducts (AGEs)—Nε-carboxymethyl-lysine (CML), Nω-carboxymethylarginine (CMA) and 3-deoxyglucosone-derived hydroimidazolone (3DG-H), and oxidative damage marker, o,o’-dityrosine (DT), age and gender had accuracy 83% (CI 79 – 89%), sensitivity 94% (CI 90–98%), specificity 67% (CI 57–76%) and area-under-the-curve of receiver operating characteristic plot (AUROC) 0.87 (CI 0.84–0.90). Inclusion of additional plasma protein glycation and oxidation adducts increased the specificity to 74%. An algorithm with 12 plasma protein glycation and oxidation adduct features was optimum for children of 1.5–12 years old: accuracy 74% (CI 70–79%), sensitivity 75% (CI 63–87%), specificity 74% (CI 58–90%) and AUROC 0.79 (CI 0.74–0.84). We conclude that ASD diagnosis may be supported using an algorithm with features of plasma protein CML, CMA, 3DG-H and DT in 5–12 years-old children, and an algorithm with additional features applicable for ASD screening in younger children. ASD severity, as assessed by ADOS-2 score, correlated positively with plasma protein glycation adducts derived from methylglyoxal, hydroimidazolone MG-H1 and Nε(1-carboxyethyl)lysine (CEL). The successful validation herein may indicate that the algorithm modifiable features are mechanistic risk markers linking ASD to increased lipid peroxidation, neuronal plasticity and proteotoxic stress.</p

A transportome-scale amiRNA-based screen identifies redundant roles of Arabidopsis ABCB6 and ABCB20 in auxin transport

Transport of signaling molecules is of major importance for regulating plant growth, development, and responses to the environment. A prime example is the spatial- distribution of auxin, which is regulated via transporters to govern developmental patterning. A critical limitation in our ability to identify transporters by forward genetic screens is their potential functional redundancy. Here, we overcome part of this functional redundancy via a transportome, multi-targeted forward-genetic screen using artificial-microRNAs (amiRNAs). We generate a library of 3000 plant lines expressing 1777 amiRNAs, designed to target closely homologous genes within subclades of transporter families and identify, genotype and quantitatively phenotype, 80 lines showing reproducible shoot growth phenotypes. Within this population, we discover and characterize a strong redundant role for the unstudied ABCB6 and ABCB20 genes in auxin transport and response. The unique multi-targeted lines generated in this study could serve as a genetic resource that is expected to reveal additional transporters

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

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p&lt;0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p&lt;0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030