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

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 middle-income 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 low-income 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 low-income, 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

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

Optique non-linéaire ultra-brève dans des cellules multipassages

This work deals with the study of nonlinear optics phenomena inside multipass cells. A Herriott cell is made of two curved mirrors that result in a stable periodic optical system, in which beams can propagate over many roundtrips. We investigate the propagation of ultrashort pulses in such a system, in which a nonlinear material (solid or gas) has been added. As a result, the optical nonlinearity is distributed over a large number of roundtrips and foci. A remarkable feature of these systems is that the output pulses do not exhibit significant spatio-spectral couplings. In this general framework, we have more specifically studied experimentally three situations. A first experiment was done to study the high nonlinearity limit in a gas-filled multipass cell. We study the output pulses properties for peak power values approaching the critical power of the gas used. We show that the output beam is essentially spectrally homogeneous, notably using a full three-dimensional optical field (amplitude and phase) characterization technique. Second, we implement a spectral compression experiment in a multipass cell including fused silica plates. By using self-phase modulation in the solid medium, we turn negatively chirped femtosecond input pulses into Fourier transform-limited picosecond pulses. This allows energy scaling compared to previous implementations of the same functionality in optical fibers. Finally, we show that, by inserting a Raman-active solid material inside a multipass cell, it is possible to convert efficiently positively chirped femtosecond pulses towards larger wavelengths. The quasi-periodic propagation of pump pulses in the cell imparts a spatial filtering effect that results in high spatial quality output Stokes beams. Taken as a whole, these experiments contribute to establishing multipass cells as an efficient and useful platform to study and use nonlinear optical phenomena.Ce manuscrit concerne l’étude de phénomènes d’optique non-linéaire dans des cellules multipassages. Une cellule d’Herriott est constituée de deux miroirs courbes qui forment un système optique périodique stable, dans lequel les faisceaux peuvent se propager sur de nombreux allers-retours. Nous étudions la propagation d’impulsions ultra-brèves dans un tel système, dans lequel un matériau non-linéaire (solide ou gaz) a été ajouté. Ainsi, la non-linéarité optique est distribuée le long de la propagation sur de multiples trajets et foyers. Une des propriétés remarquables de ces systèmes est l’absence de couplages spatio-spectraux des impulsions en sortie. Dans ce cadre, nous avons réalisé des expériences autour de trois problématiques. Une première expérience consiste à étudier la limite des hautes non-linéarités dans une cellule remplie de gaz. Nous étudions les propriétés des impulsions de sortie pour des valeurs de puissance crête approchant la puissance critique du gaz utilisé. Nous montrons que le faisceau de sortie reste essentiellement homogène spectralement, notamment en utilisant une méthode de caractérisation complète du champ optique (amplitude et phase) en trois dimensions. Dans un deuxième temps, nous réalisons une expérience de compression spectrale dans une cellule multipassage incluant des lames de silice fondue. Nous utilisons l’automodulation de phase dans le milieu solide pour transformer des impulsions d’entrée femtoseconde étirées négativement en impulsions picoseconde limitées par transformée de Fourier. Ceci permet une montée en énergie par rapport aux systèmes similaires réalisés à base de fibres optiques. Enfin, nous montrons qu’en insérant dans une cellule un milieu solide possédant des transitions Raman, il est possible de convertir de façon efficace des impulsions femtoseconde étirées positivement à des longueurs d’onde supérieures. La propagation quasi-périodique du faisceau de pompe dans la cellule engendre un effet de filtrage qui confère une bonne qualité spatiale aux faisceaux convertis. Ces résultats contribuent à établir le fait que les cellules multipassages constituent une plateforme efficace et utile pour l’étude et l’utilisation des effets non-linéaires en optique

Optique non-linéaire ultra-brève dans des cellules multipassages

This work deals with the study of nonlinear optics phenomena inside multipass cells. A Herriott cell is made of two curved mirrors that result in a stable periodic optical system, in which beams can propagate over many roundtrips. We investigate the propagation of ultrashort pulses in such a system, in which a nonlinear material (solid or gas) has been added. As a result, the optical nonlinearity is distributed over a large number of roundtrips and foci. A remarkable feature of these systems is that the output pulses do not exhibit significant spatio-spectral couplings. In this general framework, we have more specifically studied experimentally three situations. A first experiment was done to study the high nonlinearity limit in a gas-filled multipass cell. We study the output pulses properties for peak power values approaching the critical power of the gas used. We show that the output beam is essentially spectrally homogeneous, notably using a full three-dimensional optical field (amplitude and phase) characterization technique. Second, we implement a spectral compression experiment in a multipass cell including fused silica plates. By using self-phase modulation in the solid medium, we turn negatively chirped femtosecond input pulses into Fourier transform-limited picosecond pulses. This allows energy scaling compared to previous implementations of the same functionality in optical fibers. Finally, we show that, by inserting a Raman-active solid material inside a multipass cell, it is possible to convert efficiently positively chirped femtosecond pulses towards larger wavelengths. The quasi-periodic propagation of pump pulses in the cell imparts a spatial filtering effect that results in high spatial quality output Stokes beams. Taken as a whole, these experiments contribute to establishing multipass cells as an efficient and useful platform to study and use nonlinear optical phenomena.Ce manuscrit concerne l’étude de phénomènes d’optique non-linéaire dans des cellules multipassages. Une cellule d’Herriott est constituée de deux miroirs courbes qui forment un système optique périodique stable, dans lequel les faisceaux peuvent se propager sur de nombreux allers-retours. Nous étudions la propagation d’impulsions ultra-brèves dans un tel système, dans lequel un matériau non-linéaire (solide ou gaz) a été ajouté. Ainsi, la non-linéarité optique est distribuée le long de la propagation sur de multiples trajets et foyers. Une des propriétés remarquables de ces systèmes est l’absence de couplages spatio-spectraux des impulsions en sortie. Dans ce cadre, nous avons réalisé des expériences autour de trois problématiques. Une première expérience consiste à étudier la limite des hautes non-linéarités dans une cellule remplie de gaz. Nous étudions les propriétés des impulsions de sortie pour des valeurs de puissance crête approchant la puissance critique du gaz utilisé. Nous montrons que le faisceau de sortie reste essentiellement homogène spectralement, notamment en utilisant une méthode de caractérisation complète du champ optique (amplitude et phase) en trois dimensions. Dans un deuxième temps, nous réalisons une expérience de compression spectrale dans une cellule multipassage incluant des lames de silice fondue. Nous utilisons l’automodulation de phase dans le milieu solide pour transformer des impulsions d’entrée femtoseconde étirées négativement en impulsions picoseconde limitées par transformée de Fourier. Ceci permet une montée en énergie par rapport aux systèmes similaires réalisés à base de fibres optiques. Enfin, nous montrons qu’en insérant dans une cellule un milieu solide possédant des transitions Raman, il est possible de convertir de façon efficace des impulsions femtoseconde étirées positivement à des longueurs d’onde supérieures. La propagation quasi-périodique du faisceau de pompe dans la cellule engendre un effet de filtrage qui confère une bonne qualité spatiale aux faisceaux convertis. Ces résultats contribuent à établir le fait que les cellules multipassages constituent une plateforme efficace et utile pour l’étude et l’utilisation des effets non-linéaires en optique

Optique non-linéaire ultra-brève dans des cellules multipassages

Ce manuscrit concerne l’étude de phénomènes d’optique non-linéaire dans des cellules multipassages. Une cellule d’Herriott est constituée de deux miroirs courbes qui forment un système optique périodique stable, dans lequel les faisceaux peuvent se propager sur de nombreux allers-retours. Nous étudions la propagation d’impulsions ultra-brèves dans un tel système, dans lequel un matériau non-linéaire (solide ou gaz) a été ajouté. Ainsi, la non-linéarité optique est distribuée le long de la propagation sur de multiples trajets et foyers. Une des propriétés remarquables de ces systèmes est l’absence de couplages spatio-spectraux des impulsions en sortie. Dans ce cadre, nous avons réalisé des expériences autour de trois problématiques. Une première expérience consiste à étudier la limite des hautes non-linéarités dans une cellule remplie de gaz. Nous étudions les propriétés des impulsions de sortie pour des valeurs de puissance crête approchant la puissance critique du gaz utilisé. Nous montrons que le faisceau de sortie reste essentiellement homogène spectralement, notamment en utilisant une méthode de caractérisation complète du champ optique (amplitude et phase) en trois dimensions. Dans un deuxième temps, nous réalisons une expérience de compression spectrale dans une cellule multipassage incluant des lames de silice fondue. Nous utilisons l’automodulation de phase dans le milieu solide pour transformer des impulsions d’entrée femtoseconde étirées négativement en impulsions picoseconde limitées par transformée de Fourier. Ceci permet une montée en énergie par rapport aux systèmes similaires réalisés à base de fibres optiques. Enfin, nous montrons qu’en insérant dans une cellule un milieu solide possédant des transitions Raman, il est possible de convertir de façon efficace des impulsions femtoseconde étirées positivement à des longueurs d’onde supérieures. La propagation quasi-périodique du faisceau de pompe dans la cellule engendre un effet de filtrage qui confère une bonne qualité spatiale aux faisceaux convertis. Ces résultats contribuent à établir le fait que les cellules multipassages constituent une plateforme efficace et utile pour l’étude et l’utilisation des effets non-linéaires en optique.This work deals with the study of nonlinear optics phenomena inside multipass cells. A Herriott cell is made of two curved mirrors that result in a stable periodic optical system, in which beams can propagate over many roundtrips. We investigate the propagation of ultrashort pulses in such a system, in which a nonlinear material (solid or gas) has been added. As a result, the optical nonlinearity is distributed over a large number of roundtrips and foci. A remarkable feature of these systems is that the output pulses do not exhibit significant spatio-spectral couplings. In this general framework, we have more specifically studied experimentally three situations. A first experiment was done to study the high nonlinearity limit in a gas-filled multipass cell. We study the output pulses properties for peak power values approaching the critical power of the gas used. We show that the output beam is essentially spectrally homogeneous, notably using a full three-dimensional optical field (amplitude and phase) characterization technique. Second, we implement a spectral compression experiment in a multipass cell including fused silica plates. By using self-phase modulation in the solid medium, we turn negatively chirped femtosecond input pulses into Fourier transform-limited picosecond pulses. This allows energy scaling compared to previous implementations of the same functionality in optical fibers. Finally, we show that, by inserting a Raman-active solid material inside a multipass cell, it is possible to convert efficiently positively chirped femtosecond pulses towards larger wavelengths. The quasi-periodic propagation of pump pulses in the cell imparts a spatial filtering effect that results in high spatial quality output Stokes beams. Taken as a whole, these experiments contribute to establishing multipass cells as an efficient and useful platform to study and use nonlinear optical phenomena

Synthesis of hard carbons used as negative electrodes of sodium-ion batteries

Les batteries sodium-ion représentent une alternative de choix pour le stockage de l'énergie à grande échelle (domestique, réseau urbain,...). Basées sur le même principe que les batteries lithium-ion, elles présentent plusieurs avantages par rapport à ces dernières : elles utilisent des matériaux plus abondants et sont donc plus économiques, elles permettent également des cycles de charge/décharge plus rapides et sont donc capables de délivrer de plus fortes puissances. Cependant, certains points restent encore en développement, notamment la nature de l'électrode négative. L'objectif de cette thèse est de synthétiser des carbones durs performants pour l'application d'électrode négative des batteries sodium-ion en utilisant un procédé industrialisable. Ces carbones sont des carbones non-graphitisables issus de la pyrolyse de précurseurs organiques. Une étude de plusieurs précurseurs a d'abord été réalisée en mettant en valeur l'impact de certains paramètres de synthèses sur les performances électrochimiques des carbones obtenus. Le meilleur matériau, en terme de performances électrochimiques et de faisabilité industrielle, a ensuite été sélectionné et un procédé de synthèse pilote a été développéRecently, sodium-ion batteries have been intensively studied as an alternative to lithium-ion batteries for large scale energy storage (domestic, grid-scale,...). This technology, based on the same working principle as lithium-ion batteries, presents numerous advantages such as materials abundancy, economical aspects and it offers faster charge/discharge cycles, thus higher power density. However, some aspects still need to be improved such as the nature of the negative electrode material. The objective of this Ph.D. thesis is to develop an easy, simple, and effective process for the synthesis of marketable hard carbons and to improve sodium-ion battery performances. These carbons have a highly disorganized structure unlike graphite-type carbons and are usually obtained from organic precursors pyrolysis. Multiple compounds have first been tested as carbon precursors and the impact of the synthesis parameters on electrochemical performances has been highlighted. The best carbon, in terms of performances and industrial feasibility, has then been selected and a pilot process has been develope

Performance analysis and market evaluation of a low cost spectrum analyzer for IOT testing platform

This project is about designing, developing and controlling an electromechanical test bench which will be used for parallel radio spectrum measurements of company produced devices. In general the aim is to utilize all the available tools to decrease the time of testing and optimize it. The created application was developed in python language over Linux, and has the role to check, process, and send information feedback for instance power and frequency for LoRa Devices using spectrum analyzer “LTDZ”. In order to read the signal we needed to setup the right parameters that match the SA, and define in my software the samples number, step size, frequency range and others. In addition in the way how to translate the data received in a readable values. If the signal as expected we continue the process to assign specification for the device, and print them to be delivered to users with each LoRa device. Otherwise a warning led is turning under the desire device using the GPIO in the BeagleBone Black. This single process must be integrated to test an array of LoRa devices using multiple LTDZ spectrum analyzers in order to check the signals in parallel and simultaneously. The achieved goal after testing was positive, even though the spectrum analyzer had some limitations needed to be solved. In conclusion we are able to get the desired power in the specified frequency

Accurate derivation of THG conversion efficiency in periodically poled nonlinear medium and optimizing conversion parameters

We have derived a novel equation to accurately predict the third harmonic generation (THG) conversion efficiency in hybrid periodically poled nonlinear medium. Our equation considers the general case that takes both depleted pump regime and phase mismatching cases, resulting in more precise predictions of efficiency. This level of accuracy is crucial for certain applications like high-power THG lasers. Moreover, accurate calculation of THG power density is essential to prevent exceeding the crystal damage threshold. We applied our equation on hybrid MgO:PPLN crystal to determine the optimal SHG region length corresponding to two different power densities, namely, 0.25 and 0.5MW/cm2. The effect of crystal temperature on efficiency was also studies. Furthermore, a comparison between the derived equation and the commonly used nondepleted pump regime equation was performed. We found that the latter equation is significantly less accurate, particularly at high power densities, with the efficiency of the depleted pump regime being 50.6% less than nondepleted one. To demonstrate the effectiveness of the equation, our results were compared with experimental data, and we observed a good agreement between them

General solution of phase mismatched second harmonic conversion efficiency in periodically poled nonlinear medium

In this work we provide for the first time a novel and more accurate second harmonic generation (SHG) conversion efficiency equation for periodically poled nonlinear medium. We believe the equation derived in this work is more useful than equations reported in previous works which are limited because it is considering the case of either nondepleted pump regime or perfect phase matching. The equation derived in this work tackles the general case: depleted pump regime and phase mismatching which makes it important for theoretical – experimental study. We used MgO:PPLN crystal as an example to illustrate SHG conversion efficiency as function of crystal length, laser power density, crystal temperature and beam divergence. We included fundamental and second harmonic waves reflection at entrance and exit surfaces respectively and performed numerical solution using fifth-order Runge-Kutta method. The numerical results show excellent match with analytical results obtained from the derived formula. We compared our theoretical results with experimental results reported in the literature and the comparison shows a good match. Finally, we performed a comparison between depleted and nondepleted pump regime. The results show a difference of 20% between two efficiencies making nondepleted efficiency equation, which used in many theoretical – experimental comparisons, not accurate at high power densities

Impact of Preoxidation Treatments on Performances of Pitch-Based Hard Carbons for Sodium-Ion Batteries

International audienceRecently, sodium-ion batteries have been intensively studied as an alternative to lithium-ion batteries because of the abundance of sodium and its ability, for example, to answer to smart grid energy storage applications. Among all anode materials, carbonaceous materials have shown promising results, particularly hard carbons because of their high capacity and low insertion voltage (vs Na + /Na). However, these materials often suffer from their high cost and low initial Coulombic efficiency. In this paper, we investigate an easy route of hard carbon synthesis from low-cost pitch precursor. A pretreatment under a controlled atmosphere can hinder the graphitization of the pitch upon pyrolysis and induce an amorphous-like microstructure with high Na storage capacity. We also investigate the mechanism of preoxidation and show the importance of parameters optimization such as the atmosphere and the duration. This work highlights the influence of the pretreatment conditions on the hard carbon characteristics which are of key importance to explain and improve its electrochemical performances. The control of the preoxidation conditions allowed us to obtain a unique hard carbon with optimized microstructure and texture and delivering impressive electrochemical performances. This hard carbon was obtained from a 12 h pretreatment at 300°C under oxygen flow followed up by a 2 h carbonization at 1400°C under nitrogen with a high yield of 49%. This material delivers remarkable 312 mAh g −1 of reversible capacity at C/20 for only 10% of irreversibility at the first cycle, which correspond to the best electrochemical performances reported so far for pitch-based hard carbons. This work definitively emphasizes the potential of pitch-based hard carbons for further industrialization of sodium-ion batteries