Gate-induced decoupling of surface and bulk state properties in selectively-deposited Bi2_2Te3_3 nanoribbons

Three-dimensional topological insulators (TIs) host helical Dirac surface states at the interface with a trivial insulator. In quasi-one-dimensional TI nanoribbon structures the wave function of surface charges extends phase-coherently along the perimeter of the nanoribbon, resulting in a quantization of transverse surface modes. Furthermore, as the inherent spin-momentum locking results in a Berry phase offset of $\pi$ of self-interfering charge carriers an energy gap within the surface state dispersion appears and all states become spin-degenerate. We investigate and compare the magnetic field dependent surface state dispersion in selectively deposited Bi$_2$Te$_3$ TI micro- and nanoribbon structures by analysing the gate voltage dependent magnetoconductance at cryogenic temperatures. While in wide microribbon devices the field effect mainly changes the amount of bulk charges close to the top surface we identify coherent transverse surface states along the perimeter of the nanoribbon devices responding to a change in top gate potential. We quantify the energetic spacing in between these quantized transverse subbands by using an electrostatic model that treats an initial difference in charge carrier densities on the top and bottom surface as well as remaining bulk charges. In the gate voltage dependent transconductance we find oscillations that change their relative phase by $\pi$ at half-integer values of the magnetic flux quantum applied coaxial to the nanoribbon, which is a signature for a magnetic flux dependent topological phase transition in narrow, selectively deposited TI nanoribbon devices.Comment: 11 pages, 5 figure

Integration of selectively grown topological insulator nanoribbons in superconducting quantum circuits

We report on the precise integration of nm-scale topological insulator Josephson junctions into mm-scale superconducting quantum circuits via selective area epitaxy and local stencil lithography. By studying dielectric losses of superconducting microwave resonators fabricated on top of our selective area growth mask, we verify the compatibility of this in situ technique with microwave applications. We probe the microwave response of on-chip microwave cavities coupled to topological insulator-shunted superconducting qubit devices and observe a power dependence that indicates nonlinear qubit behaviour. Our method enables integration of complex networks of topological insulator nanostructures into superconducting circuits, paving the way for both novel voltage-controlled Josephson and topological qubits.Comment: 11 pages, 6 figure

Níveis de lisina digestível em rações, em que se manteve ou não a relação aminoacídica, para frangos de corte de 1 a 21 dias de idade, mantidos em estresse por calor

Dois ensaios foram conduzidos para avaliar os efeitos de níveis de lisina digestível em rações em que se manteve ou não a relação aminoacídica sobre o desempenho de frangos de corte machos de 1 a 21 dias de idade, criados em alta temperatura. O delineamento experimental utilizado em ambos os ensaios foi o inteiramente casualizado. As aves, no ensaio 1, foram distribuídas em cinco tratamentos (0,92; 0,98; 1,04; 1,10 e 1,16% de lisina digestível em ração convencional), oito repetições e dez aves por repetição. No ensaio 2, os frangos foram distribuídos em quatro tratamentos (1,04; 1,10; 1,16 e 1,22% de lisina digestível em rações mantendo a relação aminoacídica), oito repetições e dez aves por repetição. No ensaio 1, os tratamentos influenciaram quadraticamente o ganho de peso e o consumo de ração, que aumentaram até os níveis de 1,14 e 1,09% de lisina, respectivamente. Embora a conversão alimentar tenha melhorado de forma linear, o modelo LRP foi o que melhor se ajustou aos dados, estimando em 1,097% o nível de lisina a partir do qual ocorreu um platô. Não houve efeito dos tratamentos sobre os pesos absolutos do coração, fígado e intestinos, enquanto o peso absoluto da moela aumentou linearmente. O peso absoluto da carcaça aumentou, enquanto os pesos relativos do coração e do fígado reduziram quadraticamente com os tratamentos. No ensaio 2, os tratamentos influenciaram de forma linear crescente o ganho de peso e a conversão alimentar, enquanto o consumo de ração não variou. Os tratamentos influenciaram linearmente o peso absoluto da carcaça, enquanto os pesos absoluto e relativo das vísceras não variaram. Concluiu-se que frangos de corte machos, de 1 a 21 dias de idade, mantidos em estresse por calor, exigem, no mínimo, 1,14 e 1,22% de lisina digestível em ração convencional e em ração em que se manteve a relação aminoacídica, respectivamente.Two trials were conducted to evaluate the effects of digestible lysine levels in diets maintaining or not the relationship of amino acids, on performance of broilers from 1 to 21 days, kept under heat stress. A completely randomized experimental design was used in both trials. In the trial 1, the broilers were allotted in five treatments (0.92; 0.98; 1.04; 1.10 and 1.16% of lysine in conventional diets), eight replicates and ten broilers per replicate. In the trial 2, the broilers were allotted in four treatments (1.04; 1.10; 1.16 and 1.22% of lysine in diet maintaining the relationship of amino acids), eight replicates and ten broilers per replicate. In the trial 1, the digestible lysine levels influenced quadraticly the weight gain and the feed intake that increased up to 1.14 and 1.09%, respectively. Although feed:gain ratio had changed by linear way, the LRP model adjusted better to the data, estimating in 1.097% the lysine level where occurred a "plateau". There was no effect of treatments on absolute weights of heart, liver and intestines, while the absolute weight of gizzard increased linearly. The absolute weight of carcass increased while the relative weights of heart and liver reduced quadraticly. In the trial 2, the treatments influenced in a crescent linear way the weight gain and the feed:gain ratio while the feed intake was not influenced. The treatments influenced linearly the absolute weight of carcass while the absolute and relative weights of the organs were not influenced. It was concluded that male broilers, in the period from 1 to 21 days of age, kept under heat stress, require at least 1.14 and 1.22% of digestible lysine in conventional diet and in diet maintaining the relationship of amino acid, respectively

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017

A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic

Global, regional, and national progress towards Sustainable Development Goal 3.2 for neonatal and child health: all-cause and cause-specific mortality findings from the Global Burden of Disease Study 2019

Background Sustainable Development Goal 3.2 has targeted elimination of preventable child mortality, reduction of neonatal death to less than 12 per 1000 livebirths, and reduction of death of children younger than 5 years to less than 25 per 1000 livebirths, for each country by 2030. To understand current rates, recent trends, and potential trajectories of child mortality for the next decade, we present the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 findings for all-cause mortality and cause-specific mortality in children younger than 5 years of age, with multiple scenarios for child mortality in 2030 that include the consideration of potential effects of COVID-19, and a novel framework for quantifying optimal child survival. Methods We completed all-cause mortality and cause-specific mortality analyses from 204 countries and territories for detailed age groups separately, with aggregated mortality probabilities per 1000 livebirths computed for neonatal mortality rate (NMR) and under-5 mortality rate (USMR). Scenarios for 2030 represent different potential trajectories, notably including potential effects of the COVID-19 pandemic and the potential impact of improvements preferentially targeting neonatal survival. Optimal child survival metrics were developed by age, sex, and cause of death across all GBD location-years. The first metric is a global optimum and is based on the lowest observed mortality, and the second is a survival potential frontier that is based on stochastic frontier analysis of observed mortality and Healthcare Access and Quality Index. Findings Global U5MR decreased from 71.2 deaths per 1000 livebirths (95% uncertainty interval WI] 68.3-74-0) in 2000 to 37.1 (33.2-41.7) in 2019 while global NMR correspondingly declined more slowly from 28.0 deaths per 1000 live births (26.8-29-5) in 2000 to 17.9 (16.3-19-8) in 2019. In 2019,136 (67%) of 204 countries had a USMR at or below the SDG 3.2 threshold and 133 (65%) had an NMR at or below the SDG 3.2 threshold, and the reference scenario suggests that by 2030,154 (75%) of all countries could meet the U5MR targets, and 139 (68%) could meet the NMR targets. Deaths of children younger than 5 years totalled 9.65 million (95% UI 9.05-10.30) in 2000 and 5.05 million (4.27-6.02) in 2019, with the neonatal fraction of these deaths increasing from 39% (3.76 million 95% UI 3.53-4.021) in 2000 to 48% (2.42 million; 2.06-2.86) in 2019. NMR and U5MR were generally higher in males than in females, although there was no statistically significant difference at the global level. Neonatal disorders remained the leading cause of death in children younger than 5 years in 2019, followed by lower respiratory infections, diarrhoeal diseases, congenital birth defects, and malaria. The global optimum analysis suggests NMR could be reduced to as low as 0.80 (95% UI 0.71-0.86) deaths per 1000 livebirths and U5MR to 1.44 (95% UI 1-27-1.58) deaths per 1000 livebirths, and in 2019, there were as many as 1.87 million (95% UI 1-35-2.58; 37% 95% UI 32-43]) of 5.05 million more deaths of children younger than 5 years than the survival potential frontier. Interpretation Global child mortality declined by almost half between 2000 and 2019, but progress remains slower in neonates and 65 (32%) of 204 countries, mostly in sub-Saharan Africa and south Asia, are not on track to meet either SDG 3.2 target by 2030. Focused improvements in perinatal and newborn care, continued and expanded delivery of essential interventions such as vaccination and infection prevention, an enhanced focus on equity, continued focus on poverty reduction and education, and investment in strengthening health systems across the development spectrum have the potential to substantially improve USMR. Given the widespread effects of COVID-19, considerable effort will be required to maintain and accelerate progress. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd

Exploiting topological matter for Majorana physics and devices

Quantum computing promises to solve problems, which are impossible for classical computers. Among the different schemes of how to design a quantum computer, one particularly exotic version has raised a lot of attention lately. Although so-called topological quantum computing is a rather young concept, it promises to reduce the required overhead of physical quantum bits per logical quantum bit by a factor of 100–1000, due to an intrinsic protection against certain quantum errors. Once the fundamental mechanism – braiding of Majorana zero modes – is demonstrated, the topological scheme could become the most promising in terms of scalability. This article offers a short introduction to the topological concept and also aims to review the latest developments and efforts in this rapidly evolving field. In addition to this, it discusses different platforms for experimental realization of topologically protected devices. One particularly promising platform might evolve when in-situ fabrication techniques are applied to magnetically doped topological insulators. As a result, it should become possible to fabricate high fidelity Majorana devices for quantum computational tasks in a scalable fashion