The Alvarez and Lohmann refractive lenses revisited

15 pages, 10 figures.-- OCIS codes: 080.1510, 080.2740, 330.4460.Alvarez and Lohmann lenses are variable focus optical devices based on lateral shifts of two lenses with cubic-type surfaces. I analyzed the optical performance of these types of lenses computing the first order optical properties (applying wavefront refraction and propagation) without the restriction of the thin lens approximation, and the spot diagram using a ray tracing algorithm. I proposed an analytic and numerical method to select the most optimum coefficients and the specific configuration of these lenses. The results show that Lohmann composite lens is slightly superior to Alvarez one because the overall thickness and optical aberrations are smaller.I benefit from a Spanish Ministry of Science-UPM "Ramón y Cajal" contract.Peer reviewe

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Studien zur kontrollierten Freisetzung biologisch aktiver Substanzen aus resorbierbaren Nano- und Mikrosphären

The aim of the thesis was the preparation and characterization of resorbable drug delivery systems on the basis of nano- and microspheres, used as sustained release systems and for drug targeting. Using acetylic acid, the peptide hormone insulin and the serin protease thrombin studies were carried out to evaluate the impact of several process parameters of the emulsion-evaporation-method on the sphere morphology and their drug release behaviour. By immobilizing of mannose-6-phosphate entities on the surface of resorbable nanospheres, a drug targeting system for plasmids was developed by receptor-induced endocyosis. Commercially available poly(D,L-lactide) (RESOMER R 208) and poly(D,L-lactide-co-glycolide) 50:50 (RESOMER RG 504) were used as materials, both of which have a history of biomedical applications. The controlled release of bioactive substances in scaffolds for the tissue engineering is of particular interest, in addition to purely therapeutic applications. Growth-factors, in particular, can exert a positive influence on the cell proliferation and differentiation and can be incorporated into such tissue engineering systems. Within the present work, procedures were developed to equip different type of scaffolds with nano and micro spheres

Studien zur kontrollierten Freisetzung biologisch aktiver Substanzen aus resorbierbaren Nano- und Mikrosphären

The aim of the thesis was the preparation and characterization of resorbable drug delivery systems on the basis of nano- and microspheres, used as sustained release systems and for drug targeting. Using acetylic acid, the peptide hormone insulin and the serin protease thrombin studies were carried out to evaluate the impact of several process parameters of the emulsion-evaporation-method on the sphere morphology and their drug release behaviour. By immobilizing of mannose-6-phosphate entities on the surface of resorbable nanospheres, a drug targeting system for plasmids was developed by receptor-induced endocyosis. Commercially available poly(D,L-lactide) (RESOMER R 208) and poly(D,L-lactide-co-glycolide) 50:50 (RESOMER RG 504) were used as materials, both of which have a history of biomedical applications. The controlled release of bioactive substances in scaffolds for the tissue engineering is of particular interest, in addition to purely therapeutic applications. Growth-factors, in particular, can exert a positive influence on the cell proliferation and differentiation and can be incorporated into such tissue engineering systems. Within the present work, procedures were developed to equip different type of scaffolds with nano and micro spheres

Mercury migration in post-fire conditions

Актуальность исследования обусловлена необходимостью оценки выноса ртути при лесных пожарах. Лесные пожары являются катализатором миграции ртути, способствуя ее активному поступлению в атмосферу. В зависимости от типа пожара соединения ртути перераспределяются в пределах пожарища или выносятся на дальние расстояния. Цель: оценить миграцию супертоксиканта ртути в пирогенных условиях и масштабы ее воздействия на растительные компоненты и окружающую среду. Объекты: почва и растительные компоненты на территории Караканского бора, расположенного в Ордынском районе Новосибирской области, где произошел пожар смешанного типа, сочетающий низовой и повально-верховой. Методы. Отбор проб почв (n=51 штук) проведен летом 2011, 2013, 2015, 2018 гг. металлическим кольцевым пробоотборником (высота 50 мм, диаметр 84 мм), используемым для экогеохимических исследований. Отбор проб коры, веток, хвои (n=15 штук) проводили ручным способом. Пробоподготовку проводили по схеме: измельчение-квартование-взвешивание. Определение ртути выполнено атомно-абсорбционным методом «холодного пара» с использованием амальгамации на золотом сорбенте. Результаты. Проведено сравнение физико-химических характеристик проб, отобранных на фоновых и горелых территориях. Оценено содержание ртути на фоновой и горелых поверхностях. Установлено, что содержание ртути ниже на горелых площадях, а с течением времени оно снижается как на фоновых, так и на горелых поверхностях. Рассмотрено распределение ртути в системе «кора-ветви-хвоя» для образцов, отобранных на фоновых площадях. Наименьшее содержание ртути определено в образцах хвои. Проведен анализ степени поглощения ртути растениями из почвы на примере образцов листьев березы повислой (Betula Pendula Roth) и осины обыкновенной (Pópulus trémula Linnaeus), хвои сосны обыкновенной (Pínus sylvéstris Linnaeus), иван-чая узколистного (Chamerion angustifolium Linnaeus), мхов (Hylocomium splendens Bruch), лишайников (Cladina Stellaris Opiz) на фоновой и горелой поверхностях. Наибольший коэффициент поглощения имеет мох на фоновой (0,75) и горелой (1,0) поверхностях.The relevance of the research is caused by the need to assess mercury removal during forest fires. Forest fires are a catalyst for mercury migration, contributing to its active entry into the atmosphere. Mercury compounds are redistributed within the conflagration or carried over long distances, depending on the type of fire. The main aim of the research is to assess mercury supertoxicant movement in pyrogenic conditions and the extent of its impact on plant components and the environment. Objects: territory of the Karakansky boron, located in the Ordinsky district of the Novosibirsk region, where there was a mixed-type fire combining ground fire and general fire. Methods. Soil samples were taken with a steel ring (height 50 mm, diameter 84 mm) used in ecogeochemical studies. Sampling of bark, branches, needles was conducted by hand. Sample preparation was carried out according to the scheme «grinding-quartering-weighing». Mercury was determined by the atomic absorption method of «cold steam» using amalgamation on a gold sorbent. Results. The author has compared the physicochemical characteristics of the samples taken from background and burnt areas and evaluated mercury content on background and burnt surfaces. It is established that mercury content is lower on the burnt areas, and over time it decreases both on the background and on the burnt surfaces. Mercury distribution in the system «bark-branches-needles» for samples taken from background areas, was studied. The lowest mercury content is determined in needles samples. The degree of mercury absorption by plants from the soil was analyzed by the example of birch and aspen leaves, needles, Ivan tea, mosses, and lichens on the background and burnt surfaces. Moss on the background (0,75) and burnt (1,0) surfaces has the highest absorption coefficient

Evolution over Time of Ventilatory Management and Outcome of Patients with Neurologic Disease∗

OBJECTIVES: To describe the changes in ventilator management over time in patients with neurologic disease at ICU admission and to estimate factors associated with 28-day hospital mortality. DESIGN: Secondary analysis of three prospective, observational, multicenter studies. SETTING: Cohort studies conducted in 2004, 2010, and 2016. PATIENTS: Adult patients who received mechanical ventilation for more than 12 hours. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among the 20,929 patients enrolled, we included 4,152 (20%) mechanically ventilated patients due to different neurologic diseases. Hemorrhagic stroke and brain trauma were the most common pathologies associated with the need for mechanical ventilation. Although volume-cycled ventilation remained the preferred ventilation mode, there was a significant (p < 0.001) increment in the use of pressure support ventilation. The proportion of patients receiving a protective lung ventilation strategy was increased over time: 47% in 2004, 63% in 2010, and 65% in 2016 (p < 0.001), as well as the duration of protective ventilation strategies: 406 days per 1,000 mechanical ventilation days in 2004, 523 days per 1,000 mechanical ventilation days in 2010, and 585 days per 1,000 mechanical ventilation days in 2016 (p < 0.001). There were no differences in the length of stay in the ICU, mortality in the ICU, and mortality in hospital from 2004 to 2016. Independent risk factors for 28-day mortality were age greater than 75 years, Simplified Acute Physiology Score II greater than 50, the occurrence of organ dysfunction within first 48 hours after brain injury, and specific neurologic diseases such as hemorrhagic stroke, ischemic stroke, and brain trauma. CONCLUSIONS: More lung-protective ventilatory strategies have been implemented over years in neurologic patients with no effect on pulmonary complications or on survival. We found several prognostic factors on mortality such as advanced age, the severity of the disease, organ dysfunctions, and the etiology of neurologic disease

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0–4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2–6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates

Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

Background: Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation. Methods: WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109. Findings: Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0-4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2-6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital. Interpretation: In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates. Funding: European Society of Intensive Care Medicine, European Respiratory Society

Paediatric COVID-19 mortality: a database analysis of the impact of health resource disparity

Background The impact of the COVID-19 pandemic on paediatric populations varied between high-income countries (HICs) versus low-income to middle-income countries (LMICs). We sought to investigate differences in paediatric clinical outcomes and identify factors contributing to disparity between countries.Methods The International Severe Acute Respiratory and Emerging Infections Consortium (ISARIC) COVID-19 database was queried to include children under 19 years of age admitted to hospital from January 2020 to April 2021 with suspected or confirmed COVID-19 diagnosis. Univariate and multivariable analysis of contributing factors for mortality were assessed by country group (HICs vs LMICs) as defined by the World Bank criteria.Results A total of 12 860 children (3819 from 21 HICs and 9041 from 15 LMICs) participated in this study. Of these, 8961 were laboratory-confirmed and 3899 suspected COVID-19 cases. About 52% of LMICs children were black, and more than 40% were infants and adolescent. Overall in-hospital mortality rate (95% CI) was 3.3% [=(3.0% to 3.6%), higher in LMICs than HICs (4.0% (3.6% to 4.4%) and 1.7% (1.3% to 2.1%), respectively). There were significant differences between country income groups in intervention profile, with higher use of antibiotics, antivirals, corticosteroids, prone positioning, high flow nasal cannula, non-invasive and invasive mechanical ventilation in HICs. Out of the 439 mechanically ventilated children, mortality occurred in 106 (24.1%) subjects, which was higher in LMICs than HICs (89 (43.6%) vs 17 (7.2%) respectively). Pre-existing infectious comorbidities (tuberculosis and HIV) and some complications (bacterial pneumonia, acute respiratory distress syndrome and myocarditis) were significantly higher in LMICs compared with HICs. On multivariable analysis, LMIC as country income group was associated with increased risk of mortality (adjusted HR 4.73 (3.16 to 7.10)).Conclusion Mortality and morbidities were higher in LMICs than HICs, and it may be attributable to differences in patient demographics, complications and access to supportive and treatment modalities