Logical quantum processor based on reconfigurable atom arrays

Suppressing errors is the central challenge for useful quantum computing1, requiring quantum error correction (QEC)2-6 for large-scale processing. However, the overhead in the realization of error-corrected 'logical' qubits, in which information is encoded across many physical qubits for redundancy2-4, poses substantial challenges to large-scale logical quantum computing. Here we report the realization of a programmable quantum processor based on encoded logical qubits operating with up to 280 physical qubits. Using logical-level control and a zoned architecture in reconfigurable neutral-atom arrays7, our system combines high two-qubit gate fidelities8, arbitrary connectivity7,9, as well as fully programmable single-qubit rotations and mid-circuit readout10-15. Operating this logical processor with various types of encoding, we demonstrate improvement of a two-qubit logic gate by scaling surface-code6 distance from d = 3 to d = 7, preparation of colour-code qubits with break-even fidelities5, fault-tolerant creation of logical Greenberger-Horne-Zeilinger (GHZ) states and feedforward entanglement teleportation, as well as operation of 40 colour-code qubits. Finally, using 3D [[8,3,2]] code blocks16,17, we realize computationally complex sampling circuits18 with up to 48 logical qubits entangled with hypercube connectivity19 with 228 logical two-qubit gates and 48 logical CCZ gates20. We find that this logical encoding substantially improves algorithmic performance with error detection, outperforming physical-qubit fidelities at both cross-entropy benchmarking and quantum simulations of fast scrambling21,22. These results herald the advent of early error-corrected quantum computation and chart a path towards large-scale logical processors.

The Patient's perspective: A review of the results from a radiotherapy patient experience survey in the North-West of England

INTRODUCTION

A patient experience survey was undertaken for patients completing radiotherapy at the three Northwest of England Radiotherapy Providers.

METHODS

A previously reported National Radiotherapy Patient Experience Survey was adapted and undertaken in the Northwest of England. Quantitative data was analysed to establish trends. Frequency distribution was applied to appraise the number of participants selecting each of the pre-determined responses. Thematic analysis of free text responses was conducted.

RESULTS

The questionnaire received 653 responses from the 3 providers across seven departments. Thematic analysis revealed 3 themes; logistics, information and operational.

CONCLUSION

The results indicate that the majority of patients are satisfied with their treatment and care. Patients' responses indicate areas for improvements. Expectancy theory states that an individual's satisfaction is related to the difference between expected service and the service received. Consequently, when reviewing services and developing improvement it is important to understand patients' expectations^. This regional survey starts to capture what people receiving radiotherapy expect from the service and the professionals delivering their treatment.

IMPLICATIONS FOR PRACTICE

This survey responses make a case for reviewing the information provision pre and post radiotherapy. This includes clarifying the understanding of consent for treatment including the intended benefits and potential late effects. There is an argument to offer information sessions prior to radiotherapy to achieve more relaxed and informed patients. A recommendation from this work is for the radiotherapy community undertake a national radiotherapy patient experience survey, facilitated via the 11 Radiotherapy ODNs. A national radiotherapy survey has multiple benefits to inform improvements in practice. This includes benchmarking services against national averages. This approach is aligned with the principles of the service specification in terms of reducing variation and increasing quality.

Quantum optimization of maximum independent set using Rydberg atom arrays

Realizing quantum speedup for practically relevant, computationally hard problems is a central challenge in quantum information science. Using Rydberg atom arrays with up to 289 qubits in two spatial dimensions, we experimentally investigate quantum algorithms for solving the Maximum Independent Set problem. We use a hardware-efficient encoding associated with Rydberg blockade, realize closed-loop optimization to test several variational algorithms, and subsequently apply them to systematically explore a class of graphs with programmable connectivity. We find the problem hardness is controlled by the solution degeneracy and number of local minima, and experimentally benchmark the quantum algorithm's performance against classical simulated annealing. On the hardest graphs, we observe a superlinear quantum speedup in finding exact solutions in the deep circuit regime and analyze its origins.

COVID-19's Social Ecological Impacts on Health and Human Services Worker Well-being

Health and human services workers (HHS; e.g., child welfare, physical and mental healthcare) engage with clients facing heightened vulnerability during the COVID-19 pandemic. Under typical circumstances, HHS workers face a host of challenges in carrying out their job responsibilities such as high caseloads and burnout, and now navigate new challenges such as social distancing protocols and protecting their own health and that of their families and clients. This study explored the experiences of 531 HHS workers in Florida to understand well-being impacts of COVID-19 on the HHS workforce. Using a social ecological framework, we analyzed open-ended responses from HHS workers to better understand the multi-level and frequently intertwined impacts of COVID-19. Participants reported numerous proximal factors (i.e., intrapersonal, interpersonal, organizational) impacting their well-being but fewer distal factors (i.e., community, public policy). Agencies should work to understand the intersecting vulnerabilities of their workers and implement safety protocols to preserve workers' well-being.

Implications of possible interpretations of 'greenhouse gas balance' in the Paris Agreement

The main goal of the Paris Agreement as stated in Article 2 is 'holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C'. Article 4 points to this long-term goal and the need to achieve 'balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases'. This statement on 'greenhouse gas balance' is subject to interpretation, and clarifications are needed to make it operational for national and international climate policies. We study possible interpretations from a scientific perspective and analyse their climatic implications. We clarify how the implications for individual gases depend on the metrics used to relate them. We show that the way in which balance is interpreted, achieved and maintained influences temperature outcomes. Achieving and maintaining net-zero CO2-equivalent emissions conventionally calculated using GWP100 (100-year global warming potential) and including substantial positive contributions from short-lived climate-forcing agents such as methane would result in a sustained decline in global temperature. A modified approach to the use of GWP100 (that equates constant emissions of short-lived climate forcers with zero sustained emission of CO2) results in global temperatures remaining approximately constant once net-zero CO2-equivalent emissions are achieved and maintained. Our paper provides policymakers with an overview of issues and choices that are important to determine which approach is most appropriate in the context of the Paris Agreement.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

Validation of antibiotic charges in administrative data for outpatient pediatric urologic procedures

INTRODUCTION

The use of administrative health data for research has prompted questions about its validity for this purpose.

OBJECTIVE/STUDY DESIGN

The purpose of this study was to determine the concordance of Pediatric Health Information System (PHIS) perioperative antibiotic charges with the institution's medication administration data for males <10 years old and who underwent outpatient penile/inguinal procedures from July 2013 to March 2015.

RESULTS

There was 93.9% positive and negative agreement between perioperative antibiotic charges versus administration. The sensitivity and specificity were 96.8% and 87.2%, respectively. The positive and negative predictive values were 94.6% and 92.2%, respectively.

CONCLUSION

This study indicated strong agreement between PHIS pharmacy charges and medication administration.

Constraints on oceanic methane emissions west of Svalbard from atmospheric in situ measurements and Lagrangian transport modeling

Methane stored in seabed reservoirs such as methane hydrates can reach the atmosphere in the form of bubbles or dissolved in water. Hydrates could destabilize with rising temperature further increasing greenhouse gas emissions in a warming climate. To assess the impact of oceanic emissions from the area west of Svalbard, where methane hydrates are abundant, we used measurements collected with a research aircraft (Facility for Airborne Atmospheric Measurements) and a ship (Helmer Hansen) during the Summer 2014 and for Zeppelin Observatory for the full year. We present a model-supported analysis of the atmospheric CH₄ mixing ratios measured by the different platforms. To address uncertainty about where CH₄ emissions actually occur, we explored three scenarios: areas with known seeps, a hydrate stability model, and an ocean depth criterion. We then used a budget analysis and a Lagrangian particle dispersion model to compare measurements taken upwind and downwind of the potential CH₄ emission areas. We found small differences between the CH₄ mixing ratios measured upwind and downwind of the potential emission areas during the campaign. By taking into account measurement and sampling uncertainties and by determining the sensitivity of the measured mixing ratios to potential oceanic emissions, we provide upper limits for the CH₄ fluxes. The CH₄ flux during the campaign was small, with an upper limit of 2.5 nmol m^-2 s^-1 in the stability model scenario. The Zeppelin Observatory data for 2014 suggest CH₄ fluxes from the Svalbard continental platform below 0.2 Tg yr^-1. All estimates are in the lower range of values previously reported.

Measurements of δ13C in CH4 and using particle dispersion modeling to characterize sources of Arctic methane within an air mass

A stratified air mass enriched in methane (CH4) was sampled at ~600 m to ~2000 m altitude, between the north coast of Norway and Svalbard as part of the Methane in the Arctic: Measurements and Modelling campaign on board the UK's BAe-146-301 Atmospheric Research Aircraft. The approach used here, which combines interpretation of multiple tracers with transport modeling, enables better understanding of the emission sources that contribute to the background mixing ratios of CH4 in the Arctic. Importantly, it allows constraints to be placed on the location and isotopic bulk signature of the emission source(s). Measurements of δ13C in CH4 in whole air samples taken while traversing the air mass identified that the source(s) had a strongly depleted bulk δ13C CH4 isotopic signature of -70 (±2.1)‰. Combined Numerical Atmospheric-dispersion Modeling Environment and inventory analysis indicates that the air mass was recently in the planetary boundary layer over northwest Russia and the Barents Sea, with the likely dominant source of methane being from wetlands in that region.

Perspectives on family and fertility in developing countries

Abstract Two aspects of the family in relation to fertility in developing countries are discussed: set stratification within the family and extended family networks. As both these are central to J. C. Caldwell's theory of fertility transition, the paper is structured as a critique of his position. Drawing on examples and data from Asia, it is argued that the causal significance of sex stratification for fertility lies in the economic risks it imposes on women, deriving from their dependence on men, rather than, as Caldwell suggests, in the disproportionate gain that men derive from their dominant position within families. While Caldwell and others associate strong extended family networks of mutual obligation and support with persistent high fertility, it is argued here that such systems should, instead, facilitate fertility decline. Close-knit and strong kin networks can be viewed as alternatives to children as sources of insurance, and may facilitate fertility decline by preventing children from becoming the focal point of parental concerns for security.

Electron backscatter diffraction as a domain analysis technique in BiFeO(3)-PbTiO(3) single crystals

xBiFeO(3)-(1-x)PbTiO(3) single crystals were grown via a flux method for a range of compositions. Presented here is a study of the domain configuration in the 0.5BiFeO(3)-0.5PbTiO(3) composition using electron backscatter diffraction to demonstrate the ability of the technique to map ferroelastic domain structures at the micron and submicron scale. The micron-scale domains exhibit an angle of approximately 85 degrees between each variant, indicative of a ferroelastic domain wall in a tetragonal system with a spontaneous strain, c/a - 1 of 0.10, in excellent agreement with the lattice parameters derived from x-ray diffraction. Contrast seen in forescatter images is attributed to variations in the direction of the electrical polarization vector, providing images of ferroelectric domain patterns.

Analysis of the EFEMP1 gene in individuals and families with early onset drusen

AIMS

Age-related macular degeneration (AMD) is considered a complex genetic disease, although the genetic influences are not yet fully understood. Genetic analysis is hampered by the late onset of disease and the difficulty in obtaining multigenerational families. To investigate this problem further we studied our population of early onset drusen cases. The Arg345Trp mutation on exon 10 of the EGF-containing fibulin-like extracellular matrix protein 1 (EFEMP1) gene causes two clinical phenotypes of early onset drusen (Doyne honeycomb retinal dystrophy and Malattia Leventinese), yet does not appear to be involved in other early onset drusen phenotypes or typical AMD. We wished to ascertain the involvement of the EFEMP1 gene in our population of sporadic and familial subjects presenting with early onset drusen and their affected relatives.

METHODS

Individuals presenting with drusen/end-stage maculopathy at 60 years or under were identified from retinal clinics in Melbourne. All available first- and second-degree relatives were also examined. In all, 116 ethnically matched controls were collected from the same community for comparison.

RESULTS

Single stranded conformational polymorphism (SSCP) analysis and subsequent sequencing revealed four previously described and three novel sequence variations. Most occurred at similar frequencies in the case and control populations and were not thought to be disease associated.

CONCLUSION

The term early onset drusen encompasses a wide range of phenotypes and our findings indicate that it is likely that more than one gene is involved in its causation. It is essential that these clinical phenotypes are well described and categorised to allow greater possibility of success in the search for other disease genes.

Nurses need the best legal protection

Although an employer may offer staff some assistance during a legal investigation, it should not be relied on. NZNO's indemnity insurance offers members exclusive representation.

Assessment of the value of the vertebral heart scale in the radiographic diagnosis of cardiac disease in dogs

In order to assess the influence of the vertebral heart scale (VHS) on the accuracy of the radiographic diagnosis of cardiac disease, thoracic radiographs of 50 dogs with proven cardiac disease, 26 with other thoracic diseases, and 50 with no clinical signs of cardiovascular or respiratory disease were mixed and examined by three independent, blinded observers chosen to represent a range of radiographic abilities. They first examined all the radiographs without making measurements of VHS and made a diagnosis. They then re-examined the radiographs, and measured VHS on both lateral and dorsoventral or ventrodorsal radiographs before again recording a diagnosis without reference to their original diagnoses. For all the observers, the dogs with cardiac disease had a higher mean VHS than the normal dogs. A VHS over 10.7 on the lateral radiograph was a moderately accurate sign of cardiac disease. The observers' accuracy of diagnosis did not change significantly as a result of using VHS as an adjunct to a subjective assessment of the radiographs.

Working with communities for health

Nurses must continue to build links with communities to enable communities to control their own health outcomes.

A user-friendly instrument for rating agitation in dementia patients

There are many rating instruments designed to assess symptoms of agitation in patients with dementia. Most scales require that raters assess multiple specific behaviors over several days, limiting the use of such scales to clinical staff who have direct contact with patients but do not have the time to complete a comprehensive assessment following each period of observation. Also, scales that assess behavior over several days must rely on "secondhand" information describing behaviors not directly observed by the rater. The Pittsburgh Agitation Scale (PAS) is an easy-to-use instrument, based on direct observations of the patient, that was developed to monitor the severity of agitation associated with dementia. Interrater reliability and measures of validity have been established with clinical staff on a busy psychogeriatric inpatient unit and with research personnel in a nursing home setting.

Neuropeptide Y in the sympathetic control of blood pressure in hypertensive subjects

Neuropeptide Y (NPY) coexists with noradrenaline in postganglionic sympathetic neurons and with noradrenaline and adrenaline in the central nervous system. The possibility that NPY is released into the circulation during activation of the sympathoadrenal system was investigated in ten moderately hypertensive volunteers using three different stimuli. In healthy moderately hypertensive volunteers cold pressor test, head up tilt and graded bicycle exercise resulted in increased blood pressure, heart rate and plasma catecholamine concentrations. While there was a trend for plasma NPY-like immunoreactivity (NPY-LI) to increase during cold pressor test and head up tilt, NPY-LI concentration only increased significantly during bicycle exercise, the stimulus of greatest duration. These results suggest that plasma NPY-LI can be released into the circulation on sympathoadrenal activation in moderately hypertensive subjects and demonstrate that the pattern of release is similar to that previously observed in normotensive subjects.

Plasma atrial natriuretic polypeptide concentrations during and after reversion of paroxysmal supraventricular tachycardias

Plasma concentrations of immunoreactive atrial natriuretic polypeptide were raised in 22 of 23 patients with paroxysmal supraventricular tachycardia and in all seven patients with atrial flutter. Plasma concentrations of atrial natriuretic polypeptide rose soon after the onset of supraventricular tachycardia. A sample taken 30 minutes after reversion to sinus rhythm (pharmacological or non-pharmacological) showed a significant fall in 19 of the 23 patients with paroxysmal supraventricular tachycardia and all seven patients with atrial flutter. Because atrial natriuretic polypeptide has powerful natriuretic and diuretic properties, an increase may contribute considerably to the polyuria that is often associated with episodes of supraventricular tachycardia.

Complementary changes in plasma atrial natriuretic peptide and antidiuretic hormone concentrations in response to volume expansion and haemorrhage: studies in conscious normotensive and spontaneously hypertensive rats

1. Plasma concentrations of atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) were measured in conscious stroke-prone spontaneously hypertensive (SPR), spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats before and after acute volume expansion or haemorrhage. 2. Plasma ANP concentration was reduced to one-third of resting values 30 min after a 1.5% haemorrhage (1.5 ml of blood per 100 g bodyweight). Plasma ADH concentration rose immediately 50-fold on haemorrhage and remained elevated at 30 min. 3. Plasma ANP concentration increased 2.5-fold relative to resting values 1 min after infusion of 2.0 ml per 100 g 5% dextrose; after 10 min plasma ANP remained elevated. Plasma ADH concentration tended to fall on volume expansion although no significant decrease was observed. 4. There was no difference in the basal levels of ANP and ADH, or in the changes produced by alterations in blood volume, in hypertensive SPR and SHR compared with normotensive WKY. 5. Thus, plasma ANP concentrations moved in opposite directions in response to two physiological stimuli: volume expansion and haemorrhage. Reciprocal changes were observed in plasma ADH.

Direct radioimmunoassay of human plasma atrial natriuretic peptide in various normal and pathophysiological states: increase in renal and cardiac failure during exercise

We have used a sensitive direct radioimmunoassay to study the effects of exercise on plasma atrial natriuretic peptide (ANP) concentrations in man. Plasma ANP concentration increased three-fold in sixteen patients undergoing bicycle ergometer electrocardiographic tests for the investigation of chest pain. Resting ANP concentrations were higher in those patients in whom there was more evidence of heart disease, such as a positive exercise test, treatment with a beta blocker or history of myocardial infarction, although exercise resulted in increased ANP in both groups. We also confirm the increased plasma ANP concentration observed in patients with congestive cardiac failure and renal failure. In nine patients with renal failure routine haemodialysis was accompanied by a 30 per cent reduction in plasma ANP concentration. Plasma ANP concentrations were similar in treated hypertensive patients, untreated borderline hypertensive patients and normotensive subjects.