Extraordinary optical transmission and vortex excitation by periodic arrays of Fresnel zone plates

Extraordinary optical transmission and good focusing properties of a two-dimensional scattering structure is presented. The structure is made of Fresnel zone plates periodically arranged along two orthogonal directions. Each plate consists of two ring-shaped waveguides supporting modes that match the symmetry of a circularly polarized incident plane wave. High field concentration at the focal plane is obtained with short transverse and long longitudinal foci diameters. Optical vortex excitation in a paraxial region of the transmitted field is also observed and analysed in terms of cross-polarisation coupling. The structure presented may appear useful in visualization, trapping and precise manipulations of nanoparticles.Comment: 13 pages, 10 figure

A morphological study of retromolar foramen and retromolar canal of modern and medieval population

Background: Retromolar foramen (RMF) is small external orifice of the retromolar canal (RMC), located in the retromolar region of the mandible. Knowledge about the location of the RMF and the route of the RMC within the mandible is significant for clinical practice due to a high risk of injury during oral and craniomaxillofacial surgery. Materials and methods: In this study, the authors analysed 100 cone-beam computed tomography (CBCT) scans of the modern people’s retromolar region and 26 scans of samples from the medieval population. Additionally, 74 retromolar regions of the medieval people were examined macroscopically. Results: The statistical analysis showed a correlation between the frequency of RMC occurrence and bone thickness on the medial surface of the RMC. Also it was proven that the results of the RMF identification based on macroscopic examination of the bone may be falsely negative or positive and it is caused by destruction caused by resting in soil. Conclusions: Thus, CBCT is the best tool for RMF and RMC identification

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

Surface plasmon polariton generation at periodic structures

Niniejsza praca dotyczy generacji plazmonów polarytonów powierzchniowych (SPP) na asymetrycznych periodycznych strukturach metalowych. Przedstawiono wyniki numeryczne obrazujące działanie nowej konfiguracji jednowymiarowej struktury dyfrakcyjnej umożliwiającej kontrolę kierunku propagacji energii przy powierzchni przy zachowaniu padania normalnego. Warstwowa struktura składa się z dwóch różnych metalowych siatek, zanurzonych w różnych dielektrykach. Pokazano, że nawet niewielka zmiana ich przesunięcia względnego bądź zmiana kontrastu dielektrycznego może powodować zmianę kierunku propagacji energii w polu bliskim. Efekt ten może być wykorzystany przy projektowaniu urządzeń optycznych. W pracy przedstawiono także zarys metody numerycznej RCWA oraz rozszerzeń, na podstawie których opracowany został wszechstronny i zaawansowany kod numeryczny pozwalający na symulację oddziaływania pola elektromagnetycznego (EM) z wielowarstwową strukturą periodyczną o dowolnym profilu. Program umożliwia symulację padania, pod dowolnym kątem, fali płaskiej o dowolnej polaryzacji liniowej, bądź wiązki o dowolnym rozkładzie amplitudy i fazy. Możliwe jest także obliczenie spektralnych współczynników odbicia i transmisji, zależności dyspersyjnych, oraz wizualizacja rozkładu składowych pola w dowolnej płaszczyźnie. Przedstawione zostały także teoretyczne podstawy generacji i propagacji SPP. Przeprowadzono analizę modów cząstkowych wzbudzanych na metalowej strukturze jednowarstwowej pod kątem oddziaływania międzymodowego oraz transformacji modów zlokalizowanych w zdelokalizowane i ich wpływu na kierunek przepływu energii przy powierzchni. Zidentyfikowane zostały mody struktury dwuwarstwowej, ich wzajemne oddziaływanie oraz ich wpływ na odpowiedź optyczną całej struktury. Została sformułowana teza dotycząca możliwości interpretacji fizycznej działania struktury na podstawie analizy jednej z opisywanych konfiguracji. Wyjaśniono przyczyny fizyczne odpowiadające za zmianę kierunkowości propagacji energii w oparciu o analizę relacji dyspersji struktury i kierunków propagacji modów związanych z normalną do powierzchni ekwienergetycznej wyznaczoną przez wektor prędkości grupowej danego modu.The dissertation concerns the surface plasmon polariton (SPP) generation at asymmetrical periodic metal structures. Numerical results show an ability of new periodic one-dimensional configuration of metal grating to control energy propagation direction in the vicinity of the structure by a change of one of its geometrical parameters maintaining in the same time the advantage of normal incidence. The layered structure consists of two different metal gratings immersed in different dielectric media. It is showed that even a small change in the relative shift between both layers or a change in the dielectric filling contrast may redirect the energy in the near field. This effect may be useful in designing optical devices. An outline of numerical method used (RCWA) together with several extensions is given. This enabled to develop a versatile and advanced numerical code that allows to simulate electromagnetic (EM) field behaviour at multilayer periodic structures of arbitrary profile. The code allows to simulate EM field in the form of plane wave of linear polarisation impinging under the arbitrary angle or in the form of finite-diameter optical beam of arbitrary distribution of amplitude and phase. It also gives the possibility to calculate spectral transmission and reflection coefficients, dispersion relations and to visualise the distribution of field components in any plane. A theoretical basis of SPP generation and propagation is also given. An analysis of partial modes excited at one-layer metal periodic structure with the stress on modal interaction, surface-to-localized plasmon polariton transformation and their influence on the energy propagation direction near the structure is also presented. In addition, an identification of two-layered structure modes, their mutual interaction and influence on the whole optical response of the structure is given. Finally, a thesis regarding the possibility of physical interpretation of the principle of working of the asymmetrical structure is presented, based on one of the descripted configurations. On the basis of the dispersion relation analysis and modes propagation directions that are connected with the normal to equienergetic curve determined by a group velocity vector of the mode, physical reasons responsible for a change in the energy propagation direction are presented