Explore the vast range of titles available.

Objective: To provide an overview of the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) design, with particular attention to its quality control procedures. Other important methodological aspects are described in detail throughout this supplement. Design: Description of the HELENA-CSS sampling and recruitment approaches, standardization and harmonization processes, data collection and analysis strategies and quality control activities. Results: The HELENA-CSS is a multi-centre collaborative study conducted in European adolescents located in urban settings. The data management systems, quality assurance monitoring activities, standardized manuals of operating procedures and training and study management are addressed in this paper. Various quality controls to ensure collection of valid and reliable data will be discussed in this supplement, as well as quantitative estimates of measurement error. Conclusion: The great advantage of the HELENA-CSS is the strict standardization of the fieldwork and the blood analyses, which precludes to a great extent the kind of immeasurable confounding bias that often interferes when comparing results from isolated studies.

Rationale: Research involving humans is regulated by regulatory authorities through their specific requirements and controls. The Healthy Life Style in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) is a multicenter biomedical research study of adolescents in several representative European cities, which requires satisfying medico-regulatory requirements including Independent Ethics Committee (IEC) approval and agreement by the national or local regulatory authorities. To achieve a high level of quality assurance relating to ethical issues, we followed the good clinical practices (GCP) described at the International Conference on Harmonisation (ICH), which we adapted to the national and local situations of each of the 11 participating cities in 10 European countries. Objective: The main objective of the HELENA-CSS is to evaluate reliable and comparable data of nutritional habits and lifestyle in a representative sample of European adolescents. The aim of this paper is to present the methods relating to the ethical and regulatory issues of this study and to describe the current state of the medico-regulatory requirements involved in conducting this kind of study in each country. Materials and Methods: Following the GCP-ICH guidelines, a protocol describing the HELENA-CSS was written and approved by all partners. In the pilot study, a case report form adapted to the study objectives and its manual of operation was constructed and used by all partners. All information letters to adolescents and their parents and consent forms were first written in English, then translated into the local language, and adapted to each local situation. All documents were then checked centrally for any deviation and corrected if required. An operation manual relating to ethical issues and other medico-regulatory requirements was also developed. This paper presents the current status of the medico-regulatory requirements from each HELENA-CSS participant country. Results: Before the beginning of the study, most centers had satisfied the medico-regulatory requirements of IEC approval and agreement with other national or local regulatory authorities/organizations. For a few centers, some problems were detected and corrective actions were taken to improve missing information to reach a high level of quality assurance of ethical issues. Conclusion: The GCP-ICH guidelines about nontherapeutic biomedical research are interpreted and applied differently across Europe. This study shows that high-quality nontherapeutic biomedical research can address the ethical issues included in the GCP-ICH regulations and can be harmonized among the HELENA European partners.

Background/Objectives: The objectives of this study were to investigate the relationship between inflammatory parameters (CRP, c-reactive protein; AGP, α1-acid glycoprotein), iron status indicators (SF, serum ferritin; sTfR, soluble transferrin receptor) and body mass index (BMI) z-score, fat-free mass (FFM) and fat mass (FM) in European adolescents. Differences in intake for some nutrients (total iron, haem and non-haem iron, vitamin C, calcium, proteins) were assessed according to BMI categories, and the association of nutrient intakes with BMI z-score, FM and FFM was evaluated. Methods: A total of 876 adolescents participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence-Cross Sectional Study were included in the study sample. Results: Mean CRP values (standard error; s.e.) were significantly higher in overweight/obese adolescents (1.7±0.3 and 1.4±0.3 mg/l in boys and girls, respectively) than in thin/normal-weight adolescents (1.1±0.2 and 1.0±0.1 mg/l in boys and girls, respectively) ( P <0.05). For boys, mean SF values (s.e.) were significantly higher in overweight/obese adolescents (46.9±2.7 μg/l) than in thin/normal-weight adolescents (35.7±1.7 μg/l) ( P <0.001), whereas median sTfR values did not differ among BMI categories for both boys and girls. Multilevel regression analyses showed that BMI z-score and FM were significantly related to CRP and AGP ( P <0.05). Dietary variables did not differ significantly among BMI categories, except for the intake of vegetable proteins, which, for boys, was higher in thin/normal-weight adolescents than in overweight/obese adolescents ( P <0.05). Conclusions: The adiposity of the European adolescents was sufficient to cause chronic inflammation but not sufficient to impair iron status and cause iron deficiency.

Objective: Neuromedin B (NMB) is a bombesin-like peptide, which inhibits food intake and modulates stress-related behaviour. An NMB gene polymorphism (P73T) has been earlier associated with obesity and abnormal eating behaviour in adults. Methods: The association between four NMB polymorphisms and obesity-related phenotypes was investigated in the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study (n=1144, 12–17-year-old European adolescents). This population was genotyped for the NMB rs1107179, rs17598561, rs3809508 and rs1051168 (P73T) polymorphisms. Obesity was defined according to Cole et al. (BMJ 2000; 320:1240–1243) criteria; eating behaviour was assessed by the Eating Behaviour and Weight Problems Inventory for Children (EWI-C) and the food choices and preferences questionnaires. Familial socioeconomic status (SES) was assessed through the parents’ educational level. Results: Only the genotype distribution of rs3809508 differed according to obesity status, as the TT genotype was more frequent in obese than in non-obese adolescents (8.6% vs 3.1%, P=0.05; adjusted odds ratio for obesity (95% confidence interval): 2.85 (1.11–7.31), P=0.03). Moreover, TT subjects had higher body mass index (22.8±4.4 kg m–2 vs 21.3±3.7 kg m–2, P=0.02), waist circumference (75.8±9.7 cm vs 72.2±9.3 cm, P=0.006), waist-to-hip ratio (0.84±0.14 vs 0.79±0.07, P<0.0001) and waist-to-height ratio (0.47±0.06 vs 0.44±0.55, P=0.002) than C allele carriers. The effects of this single nucleotide polymorphism on all anthropometric values were influenced by the maternal SES, in that a low maternal educational level aggravated the phenotype of adolescents carrying the TT genotype (interactions: P<0.02). No association with EWI-C scores was found, although sweet craving was a more frequent cause of between-meal food intake in TT subjects than in C allele carriers (24.3% vs 9.2%, P=0.01). Conclusion: In European adolescents, the TT genotype of the NMB rs3809508 polymorphism was associated with a higher risk of obesity. Moreover, the effects of this polymorphism on anthropometric values were influenced by the maternal educational level.

To identify the main knowledge gaps and to propose research lines that will be developed within the European Union-funded 'Healthy Lifestyle in Europe by Nutrition in Adolescence' (HELENA) project, concerning the nutritional status, physical fitness and physical activity of adolescents in Europe. Review of the currently existing literature. The main gaps identified were: lack of harmonised and comparable data on food intake; lack of understanding regarding the role of eating attitudes, food choices and food preferences; lack of harmonised and comparable data on levels and patterns of physical activity and physical fitness; lack of comparable data about obesity prevalence and body composition; lack of comparable data about micronutrient and immunological status; and lack of effective intervention methodologies for healthier lifestyles. The HELENA Study Group should develop, test and describe harmonised and state-of-the-art methods to assess the nutritional status and lifestyle of adolescents across Europe; develop and evaluate an intervention on eating habits and physical activity; and develop and test new healthy food products attractive for European adolescents.

The HELENA Project—Healthy Lifestyle in Europe by Nutrition in Adolescence—is a European, collaborative research project financed by the EU Sixth Framework Programme in the area of nutrition-related adolescent health. The basic objective of the HELENA project is to obtain reliable and comparable data from a random sample of European adolescents (boys and girls aged 13–16 years) on a broad battery of relevant nutrition and health-related parameters: dietary intake, food choices and preferences, anthropometry, serum indicators of lipid metabolism and glucose metabolism, vitamin and mineral status, immunological markers, physical activity, fitness and genetic markers. The HELENA project is conceived as a scientific construction with four complementary sub-studies that are elaborated through 14 well-defined work packages. Sub-studies are focused, respectively, on “a cross-sectional description of lifestyles and indicators of nutritional status (HELENA-CSS)”, “a lifestyle education intervention programme (HELENA-LSEI), “a metabolic study with cross-over design (HELENA-COMS)” and a “study on behaviour, food preferences and food development” (HELENA-BEFO). The project unites 20 research centres from 10 European countries. In addition, the consortium comprises five SMEs (small and medium-sized enterprises) that are actively involved in the research activities. The core of the HELENA project study material is an overall European cohort of 3,000 adolescents, equally recruited in ten cities from nine countries. Standardization of methods among partners is a key issue in the project and is obtained through the development of standard protocols, training sessions, validation sub-studies and pilot projects. Health-related problems have a tendency to evolve in cycles, with ever new problems emerging in ever new contexts that call for appropriate and tailored actions. The HELENA project is expected to offer essential elements for use in the overall machinery of required public health nutrition cycles. It is of the greatest importance for its results to prove useful that it can communicate with other initiatives on the level of science and society.

Single-electron spin qubits employ magnetic fields on the order of 1 Tesla or above to enable quantum state readout via spin-dependent-tunnelling. This requires demanding microwave engineering for coherent spin resonance control, which limits the prospects for large scale multi-qubit systems. Alternatively, singlet-triplet readout enables high-fidelity spin-state measurements in much lower magnetic fields, without the need for reservoirs. Here, we demonstrate low-field operation of metal-oxide-silicon quantum dot qubits by combining coherent single-spin control with high-fidelity, single-shot, Pauli-spin-blockade-based ST readout. We discover that the qubits decohere faster at low magnetic fields with T 2 Rabi = 18.6  μs and T 2 * = 1.4  μs at 150 mT. Their coherence is limited by spin flips of residual 29 Si nuclei in the isotopically enriched 28 Si host material, which occur more frequently at lower fields. Our finding indicates that new trade-offs will be required to ensure the frequency stabilization of spin qubits, and highlights the importance of isotopic enrichment of device substrates for the realization of a scalable silicon-based quantum processor. One of the main sources of decoherence in silicon electron spin qubits is their interaction with nearby fluctuating nuclear spins. Zhao et al. present a device made from enriched silicon to reduce the nuclear spin density and find its performance is still limited by fluctuations of residual spins.

A fault-tolerant quantum processor may be configured using stationary qubits interacting only with their nearest neighbours, but at the cost of significant overheads in physical qubits per logical qubit. Such overheads could be reduced by coherently transporting qubits across the chip, allowing connectivity beyond immediate neighbours. Here we demonstrate high-fidelity coherent transport of an electron spin qubit between quantum dots in isotopically-enriched silicon. We observe qubit precession in the inter-site tunnelling regime and assess the impact of qubit transport using Ramsey interferometry and quantum state tomography techniques. We report a polarization transfer fidelity of 99.97% and an average coherent transfer fidelity of 99.4%. Our results provide key elements for high-fidelity, on-chip quantum information distribution, as long envisaged, reinforcing the scaling prospects of silicon-based spin qubits. Long-range coherent spin-qubit transfer between semiconductor quantum dots requires understanding and control over associated errors. Here, the authors achieve high-fidelity coherent state transfer in a Si double quantum dot, underpinning the prospects of a large-scale quantum computer.

The encoding of qubits in semiconductor spin carriers has been recognized as a promising approach to a commercial quantum computer that can be lithographically produced and integrated at scale 1 – 10 . However, the operation of the large number of qubits required for advantageous quantum applications 11 – 13 will produce a thermal load exceeding the available cooling power of cryostats at millikelvin temperatures. As the scale-up accelerates, it becomes imperative to establish fault-tolerant operation above 1 K, at which the cooling power is orders of magnitude higher 14 – 18 . Here we tune up and operate spin qubits in silicon above 1 K, with fidelities in the range required for fault-tolerant operations at these temperatures 19 – 21 . We design an algorithmic initialization protocol to prepare a pure two-qubit state even when the thermal energy is substantially above the qubit energies and incorporate radiofrequency readout to achieve fidelities up to 99.34% for both readout and initialization. We also demonstrate single-qubit Clifford gate fidelities up to 99.85% and a two-qubit gate fidelity of 98.92%. These advances overcome the fundamental limitation that the thermal energy must be well below the qubit energies for the high-fidelity operation to be possible, surmounting a main obstacle in the pathway to scalable and fault-tolerant quantum computation. Initialization and operation of spin qubits in silicon above 1 K reach fidelities sufficient for fault-tolerant operations at these temperatures.

Once called a ‘classically non-describable two-valuedness’ by Pauli, the electron spin forms a qubit that is naturally robust to electric fluctuations. Paradoxically, a common control strategy is the integration of micromagnets to enhance the coupling between spins and electric fields, which, in turn, hampers noise immunity and adds architectural complexity. Here we exploit a switchable interaction between spins and orbital motion of electrons in silicon quantum dots, without a micromagnet. The weak effects of relativistic spin–orbit interaction in silicon are enhanced, leading to a speed up in Rabi frequency by a factor of up to 650 by controlling the energy quantization of electrons in the nanostructure. Fast electrical control is demonstrated in multiple devices and electronic configurations. Using the electrical drive, we achieve a coherence time T 2,Hahn  ≈ 50 μs, fast single-qubit gates with T π/2  = 3 ns and gate fidelities of 99.93%, probed by randomized benchmarking. High-performance all-electrical control improves the prospects for scalable silicon quantum computing. High-performance all-electrical control is a prerequisite for scalable silicon quantum computing. The switchable interaction between spins and orbital motion of electrons in silicon quantum dots now enables the electrical control of a spin qubit with high fidelity and speed, without the need for integrating a micromagnet.