Spin-polarized hydrogen adsorbed on the surface of superfluid He-4

The experimental realization of a thin layer of spin-polarized hydrogen H double down arrow adsorbed on top of the surface of superfluid He-4 provides one of the best examples of a stable, nearly two-dimensional(2D) quantum Bose gas. We report a theoretical study of this system using quantum Monte Carlo methods in the limit of zero temperature. Using the full Hamiltonian of the system, composed of a superfluid He-4 slab and the adsorbed H double down arrow layer, we calculate the main properties of its ground state using accurate models for the pair interatomic potentials. Comparing the results for the layer with the ones obtained for a strictly 2D setup, we analyze the departure from the 2D character when the density increases. Only when the coverage is rather small the use of a purely 2D model is justified. The condensate fraction of the layer is significantly larger than in 2D at the same surface density, being as large as 60% at the largest coverage studied. (c) 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4843375]Postprint (published version

Morbidity and mortality after anaesthesia in early life: results of the European prospective multicentre observational study, neonate and children audit of anaesthesia practice in Europe (NECTARINE)

Background: Neonates and infants requiring anaesthesia are at risk of physiological instability and complications, but triggers for peri-anaesthetic interventions and associations with subsequent outcome are unknown. Methods: This prospective, observational study recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. The primary aim was to identify thresholds of pre-determined physiological variables that triggered a medical intervention. The secondary aims were to evaluate morbidities, mortality at 30 and 90 days, or both, and associations with critical events. Results: Infants (n=5609) born at mean (standard deviation [SD]) 36.2 (4.4) weeks postmenstrual age (35.7% preterm) underwent 6542 procedures within 63 (48) days of birth. Critical event(s) requiring intervention occurred in 35.2% of cases, mainly hypotension (>30% decrease in blood pressure) or reduced oxygenation (SpO2 <85%). Postmenstrual age influenced the incidence and thresholds for intervention. Risk of critical events was increased by prior neonatal medical conditions, congenital anomalies, or both (relative risk [RR]=1.16; 95% confidence interval [CI], 1.04–1.28) and in those requiring preoperative intensive support (RR=1.27; 95% CI, 1.15–1.41). Additional complications occurred in 16.3% of patients by 30 days, and overall 90-day mortality was 3.2% (95% CI, 2.7–3.7%). Co-occurrence of intraoperative hypotension, hypoxaemia, and anaemia was associated with increased risk of morbidity (RR=3.56; 95% CI, 1.64–7.71) and mortality (RR=19.80; 95% CI, 5.87–66.7). Conclusions: Variability in physiological thresholds that triggered an intervention, and the impact of poor tissue oxygenation on patient's outcome, highlight the need for more standardised perioperative management guidelines for neonates and infants. Clinical trial registration: NCT02350348

Difficult tracheal intubation in neonates and infants. NEonate and Children audiT of Anaesthesia pRactice IN Europe (NECTARINE): a prospective European multicentre observational study

Background: Neonates and infants are susceptible to hypoxaemia in the perioperative period. The aim of this study was to analyse interventions related to anaesthesia tracheal intubations in this European cohort and identify their clinical consequences. Methods: We performed a secondary analysis of tracheal intubations of the European multicentre observational trial (NEonate and Children audiT of Anaesthesia pRactice IN Europe [NECTARINE]) in neonates and small infants with difficult tracheal intubation. The primary endpoint was the incidence of difficult intubation and the related complications. The secondary endpoints were the risk factors for severe hypoxaemia attributed to difficult airway management, and 30 and 90 day outcomes. Results: Tracheal intubation was planned in 4683 procedures. Difficult tracheal intubation, defined as two failed attempts of direct laryngoscopy, occurred in 266 children (271 procedures) with an incidence (95% confidence interval [CI]) of 5.8% (95% CI, 5.1e6.5). Bradycardia occurred in 8% of the cases with difficult intubation, whereas a significant decrease in oxygen saturation (SpO2<90% for 60 s) was reported in 40%. No associated risk factors could be identified among comorbidities, surgical, or anaesthesia management. Using propensity scoring to adjust for confounders, difficult anaesthesia tracheal intubation did not lead to an increase in 30 and 90 day morbidity or mortality. Conclusions: The results of the present study demonstrate a high incidence of difficult tracheal intubation in children less than 60 weeks post-conceptual age commonly resulting in severe hypoxaemia. Reassuringly, the morbidity and mortality at 30 and 90 days was not increased by the occurrence of a difficult intubation event. Clinical trial registration: NCT02350348

Morbidity and mortality after anaesthesia in early life: results of the European prospective multicentre observational study, neonate and children audit of anaesthesia practice in Europe (NECTARINE)

BACKGROUND: Neonates and infants requiring anaesthesia are at risk of physiological instability and complications, but triggers for peri-anaesthetic interventions and associations with subsequent outcome are unknown. METHODS: This prospective, observational study recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. The primary aim was to identify thresholds of pre-determined physiological variables that triggered a medical intervention. The secondary aims were to evaluate morbidities, mortality at 30 and 90 days, or both, and associations with critical events. RESULTS: Infants (n=5609) born at mean (standard deviation [sd]) 36.2 (4.4) weeks postmenstrual age (35.7% preterm) underwent 6542 procedures within 63 (48) days of birth. Critical event(s) requiring intervention occurred in 35.2% of cases, mainly hypotension (>30% decrease in blood pressure) or reduced oxygenation (SpO2 <85%). Postmenstrual age influenced the incidence and thresholds for intervention. Risk of critical events was increased by prior neonatal medical conditions, congenital anomalies, or both (relative risk [RR]=1.16; 95% confidence interval [CI], 1.04–1.28) and in those requiring preoperative intensive support (RR=1.27; 95% CI, 1.15–1.41). Additional complications occurred in 16.3% of patients by 30 days, and overall 90-day mortality was 3.2% (95% CI, 2.7–3.7%). Co-occurrence of intraoperative hypotension, hypoxaemia, and anaemia was associated with increased risk of morbidity (RR=3.56; 95% CI, 1.64–7.71) and mortality (RR=19.80; 95% CI, 5.87–66.7). CONCLUSIONS: Variability in physiological thresholds that triggered an intervention, and the impact of poor tissue oxygenation on patient's outcome, highlight the need for more standardised perioperative management guidelines for neonates and infants

Difficult tracheal intubation in neonates and infants. NEonate and Children audiT of Anaesthesia pRactice IN Europe (NECTARINE): a prospective European multicentre observational study

BACKGROUND: Neonates and infants are susceptible to hypoxaemia in the perioperative period. The aim of this study was to analyse interventions related to anaesthesia tracheal intubations in this European cohort and identify their clinical consequences. METHODS: We performed a secondary analysis of tracheal intubations of the European multicentre observational trial (NEonate and Children audiT of Anaesthesia pRactice IN Europe [NECTARINE]) in neonates and small infants with difficult tracheal intubation. The primary endpoint was the incidence of difficult intubation and the related complications. The secondary endpoints were the risk factors for severe hypoxaemia attributed to difficult airway management, and 30 and 90 day outcomes. RESULTS: Tracheal intubation was planned in 4683 procedures. Difficult tracheal intubation, defined as two failed attempts of direct laryngoscopy, occurred in 266 children (271 procedures) with an incidence (95% confidence interval [CI]) of 5.8% (95% CI, 5.1–6.5). Bradycardia occurred in 8% of the cases with difficult intubation, whereas a significant decrease in oxygen saturation (SpO2<90% for 60 s) was reported in 40%. No associated risk factors could be identified among co-morbidities, surgical, or anaesthesia management. Using propensity scoring to adjust for confounders, difficult anaesthesia tracheal intubation did not lead to an increase in 30 and 90 day morbidity or mortality. CONCLUSIONS: The results of the present study demonstrate a high incidence of difficult tracheal intubation in children less than 60 weeks post-conceptual age commonly resulting in severe hypoxaemia. Reassuringly, the morbidity and mortality at 30 and 90 days was not increased by the occurrence of a difficult intubation event

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

Sustainable and energy neutral 'European house' in Rwanda

The importance of energy and sustainability issues related to buildings and built environment is constantly increasing. Developed countries are already dealing with these issues by adjusting their building codes and by introducing sustainability assessment methods as an important part of building projects. But how can developing countries with all its challenges and a focus that is understandingly more pointed towards escaping poverty than thinking about long term sustainability deal with these issues? In this thesis, I assessed the possibilities for an integral design of an energy neutral and sustainable office building in Rwanda, a small country in the heart of Africa and one of the few developing countries that is progressing very fast. I chose to work out the design of a - potentially to be built - office space where the embassies of 6 EU countries could set up office, a project that I named the 'European House'. The main research question of this study is How can a European house in Kigali be optimally designed in an energy neutral and sustainable way? To find answers to this question, the climate of the location, its challenges and opportunities in terms of building design were studied. I also researched locally available construction materials and in general construction materials that could be applied on the project. To get some quantitative values of sustainable issues, a few rating systems were considered. Eventually, I applied the BREEAM International rating system and described how, in this specific context, the European House could score an outstanding rate. Following a literature study, case studies were introduced in order to see what kind of strategies did similar projects use in similar climates (Kenia, Zimbabwe and Malaysia) and what were their achievements regarding sustainability issues. As the European House physically did not exist, some space limitations/dimension requirements needed to be determined by interviewing potential users of the EU House. Representatives of 5 embassies in Kigali filled in my questionnaire, describing their potential spatial requirements, which helped defining the size of building and set further boundaries for the sketch design of the European House. The following conclusions have been drawn based on the proposed sketch design: Use of local/regional building materials Multi-story buildings are almost exclusively made out of concrete in Rwanda, with currently very little focus on sustainability. Recently increased tax rates on cement imported out of east African community will hopefully contribute to the reduction of the embodied energy of the concrete used in Rwanda. With high demand of concrete on one side and its low availability on the other, Rwandan building market will have to search for some appropriate alternatives. When applying timber bearing structure on the European House, the total environmental cost of the bearing structure is 0,21€ per m2 GFA. In this case, the wooden bearing structure offers much less environmental impact than other possible solutions (concrete and steel) and therefore it is the preferred choice. However, timber in Rwandan constructions is still not being used in structural applications, even though it offers great potentials and it is available and possible to be imported from DR Congo – Rwanda’s neighboring country. Passive and active design strategies The following passive strategies proved to be effective in the Kigali climate and could therefor be applied to the European House design: Orientation – long narrowly designed buildings with long side along north/south facade Shading devices – horizontal devices should be installed on northern and southern facades Size of windows: wall/window/ratio should be at least 40%, European House window dimensions should be 1,8x1,8m Natural ventilation: On the proposed design of the European House, the best applicable method is natural side ventilation Active design strategies Focusing on sun and wind local potentials, Energy potential mapping gives encouraging results. Most of the locally available energy could be obtained from the sun, in case all the roof area would be covered by Photovoltaics. In order to assure buildings self-efficiency, it is essential to have an energy storage system/battery, to be able to use the harvested energy in different moments if needed. In the Equator area (which is the case in Rwanda), the solar generation does not change a lot during the year and therefore no large amount of storage is needed. Storage that equals to 3,5 days of average generation should serve as a reasonable backup (this equals to the storage capacity of 1061 kwh in case of Rwanda). In conclusion - with integrating passive and active design strategies on the European House design, 2,5 times more energy is obtained than required. BREEAM International sustainable assessment BREEAM proved to be a very useful tool on the road to sustainable and energy neutral design in the Rwandan context. BREEAM International credits studied in the Rwandan context show that most of them are actually possible to reach, assuming that the project team is experienced in the BREEAM field and that clear goals are set from the very beginning of each project. In theory there are no real obstacles to obtain high credit scores in the Rwanda. However some of the BREEAM International credits would need to be adapted to the local Rwandan context. This regards mostly the credits that are referenced to the local legislations. In conclusion – the example of the European House in Kigali shows that an energy neutral and sustainable office building is possible in Rwanda. Perfect climate conditions and renewable energy potentials are there, to be discovered and used in a smart and responsible way. Rwanda of course misses many things, without which some parts of my analysis would be hard to materialize – like an environmental database for different types of construction materials. Further more, many parts of the BREEAM analysis are assumed to be achieved under good management and financial means which are both hard to find in Rwanda. However, the realization of this or a similar project could inspire a new way to look at possibilities for sustainable and energy neutral buildings in Rwanda. Recommendations for other developing countries · Make a climate study of the location a ‘must’ for any type of construction project in order to reduce the overall energy costs and building performance, even if this is not required by local building regulations · Introducing sustainable assessment methods (BREEAM International) in projects in developing countries encourages the use of passive strategies and influences sustainable outcomes. BREEAM International is a valuable tool to be applied on projects in developing countries. However, when certain datas are not available, one needs to be resourceful · Often the choices of materials applied for structures is related to the fact that local workers only know specific methods and are ‘afraid to build differently’; Rwanda’s recent example shows that local workers can easily be trained to use different building techniques · The benefits and high potentials of sustainable and energy neutral buildings in developing countries need to be better explained and promoted to all parties involved. Suggestions for further research based on this thesis · Further improvement of other widely used construction materials (adobe bricks) and their structural application in multi story buildings in Rwanda · Possibilities of creating a Rwanda National scheme based on BREEAM International Assessment · Challenges of building techniques from vernacular to modern in Rwanda · In case of rising temperatures due to climate change, what kind of consequences would this have on the natural ventilation possibilities in European HouseCivil Engineering and GeosciencesStructural EngineeringBuilding Engineerin