How production networks amplify economic growth.

Technological improvement is the most important cause of long-term economic growth. In standard growth models, technology is treated in the aggregate, but an economy can also be viewed as a network in which producers buy goods, convert them to new goods, and sell the production to households or other producers. We develop predictions for how this network amplifies the effects of technological improvements as they propagate along chains of production, showing that longer production chains for an industry bias it toward faster price reduction and that longer production chains for a country bias it toward faster growth. These predictions are in good agreement with data from the World Input Output Database and improve with the passage of time. The results show that production chains play a major role in shaping the long-term evolution of prices, output growth, and structural change.

Hosing of a Long Relativistic Particle Bunch in Plasma.

Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven by a short, misaligned preceding bunch. Hosing develops in the plane of misalignment, self-modulation in the perpendicular plane, at frequencies close to the plasma electron frequency, and are reproducible. Development of hosing depends on misalignment direction, its growth on misalignment extent and on proton bunch charge. Results have the main characteristics of a theoretical model, are relevant to other plasma-based accelerators and represent the first characterization of hosing.

Acceleration of electrons in the plasma wakefield of a proton bunch.

High-energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. To increase the energy of the particles or to reduce the size of the accelerator, new acceleration schemes need to be developed. Plasma wakefield acceleration1-5, in which the electrons in a plasma are excited, leading to strong electric fields (so called 'wakefields'), is one such promising acceleration technique. Experiments have shown that an intense laser pulse6-9 or electron bunch10,11 traversing a plasma can drive electric fields of tens of gigavolts per metre and above-well beyond those achieved in conventional radio-frequency accelerators (about 0.1 gigavolt per metre). However, the low stored energy of laser pulses and electron bunches means that multiple acceleration stages are needed to reach very high particle energies5,12. The use of proton bunches is compelling because they have the potential to drive wakefields and to accelerate electrons to high energy in a single acceleration stage13. Long, thin proton bunches can be used because they undergo a process called self-modulation14-16, a particle-plasma interaction that splits the bunch longitudinally into a series of high-density microbunches, which then act resonantly to create large wakefields. The Advanced Wakefield (AWAKE) experiment at CERN17-19 uses high-intensity proton bunches-in which each proton has an energy of 400 gigaelectronvolts, resulting in a total bunch energy of 19 kilojoules-to drive a wakefield in a ten-metre-long plasma. Electron bunches are then injected into this wakefield. Here we present measurements of electrons accelerated up to two gigaelectronvolts at the AWAKE experiment, in a demonstration of proton-driven plasma wakefield acceleration. Measurements were conducted under various plasma conditions and the acceleration was found to be consistent and reliable. The potential for this scheme to produce very high-energy electron bunches in a single accelerating stage20 means that our results are an important step towards the development of future high-energy particle accelerators21,22.

How market ecology explains market malfunction.

Standard approaches to the theory of financial markets are based on equilibrium and efficiency. Here we develop an alternative based on concepts and methods developed by biologists, in which the wealth invested in a financial strategy is like the abundance of a species. We study a toy model of a market consisting of value investors, trend followers, and noise traders. We show that the average returns of strategies are strongly density dependent; that is, they depend on the wealth invested in each strategy at any given time. In the absence of noise, the market would slowly evolve toward an efficient equilibrium, but the statistical uncertainty in profitability (which is calibrated to match real markets) makes this noisy and uncertain. Even in the long term, the market spends extended periods of time away from perfect efficiency. We show how core concepts from ecology, such as the community matrix and food webs, give insight into market behavior. For example, at the efficient equilibrium, all three strategies have a mutualistic relationship, meaning that an increase in the wealth of one increases the returns of the others. The wealth dynamics of the market ecosystem explain how market inefficiencies spontaneously occur and gives insight into the origins of excess price volatility and deviations of prices from fundamental values.

Emergent inequality and business cycles in a simple behavioral macroeconomic model.

Standard macroeconomic models assume that households are rational in the sense that they are perfect utility maximizers and explain economic dynamics in terms of shocks that drive the economy away from the steady state. Here we build on a standard macroeconomic model in which a single rational representative household makes a savings decision of how much to consume or invest. In our model, households are myopic boundedly rational heterogeneous agents embedded in a social network. From time to time each household updates its savings rate by copying the savings rate of its neighbor with the highest consumption. If the updating time is short, the economy is stuck in a poverty trap, but for longer updating times economic output approaches its optimal value, and we observe a critical transition to an economy with irregular endogenous oscillations in economic output, resembling a business cycle. In this regime households divide into two groups: poor households with low savings rates and rich households with high savings rates. Thus, inequality and economic dynamics both occur spontaneously as a consequence of imperfect household decision-making. Adding a few "rational" agents with a fixed savings rate equal to the long-term optimum allows us to match business cycle timescales. Our work here supports an alternative program of research that substitutes utility maximization for behaviorally grounded decision-making.

Controlled Growth of the Self-Modulation of a Relativistic Proton Bunch in Plasma.

A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self-modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility and control are at the level of a small fraction of the modulation period. With this seeding method, we independently control the amplitude of the seed wakefields with the charge of the electron bunch and the growth rate of SM with the charge of the proton bunch. Seeding leads to larger growth of the wakefields than in the instability case.

Forecasting the propagation of pandemic shocks with a dynamic input-output model.

We introduce a dynamic disequilibrium input-output model that was used to forecast the economics of the COVID-19 pandemic. This model was designed to understand the upstream and downstream propagation of the industry-specific demand and supply shocks caused by COVID-19, which were exceptional in their severity, suddenness and heterogeneity across industries. The model, which was inspired in part by previous work on the response to natural disasters, includes the introduction of a new functional form for production functions, which allowed us to create bespoke production functions for each industry based on a survey of industry analysts. We also introduced new elements for modeling inventories, consumption and labor. The resulting model made accurate real-time forecasts for the decline of sectoral and aggregate economic activity in the United Kingdom in the second quarter of 2020. We examine some of the theoretical implications of our model and find that the choice of production functions and inventory levels plays a key role in the propagation of pandemic shocks. Our work demonstrates that an out of equilibrium model calibrated against national accounting data can serve as a useful real time policy evaluation and forecasting tool.

Valuing the Future and Discounting in Random Environments: A Review.

We address the process of discounting in random environments, which allows valuation of the future in economic terms. We review several approaches to the problem regarding different well-established stochastic market dynamics in the continuous-time context and include the Feynman-Kac approach. We also review the relation between bond-pricing theory and discounting and introduce both the market price of risk and the risk neutral measure from an intuitive point of view devoid of excessive formalism. We provide the discount for each economic model and discuss their key results. We finally present a summary of our previous empirical studies for several countries on the long-run discount problem.

Transition between Instability and Seeded Self-Modulation of a Relativistic Particle Bunch in Plasma.

We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude [≥(4.1±0.4) MV/m], the phase of the modulation along the bunch is reproducible from event to event, with 3%-7% (of 2π) rms variations all along the bunch. The phase is not reproducible for lower initial amplitudes. We observe the transition between these two regimes. Phase reproducibility is essential for deterministic external injection of particles to be accelerated.

Proton Bunch Self-Modulation in Plasma with Density Gradient.

We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory.

Conservation of the name Aeromonas eucrenophila over the name Aeromonas punctata for the organism based on type stain NCMB 74T and universally defined as 'Aeromonas DNA hybridization group 6'.

In a companion paper, we requested the Judicial Commission to correct the type strain of Aeromonas punctata from ATCC 15468T to NCMB 74T (=ATCC 23309T). Correction of this error on the 1980 Approved Lists by an Opinion of the Judicial Commission will remove the status of the name Aeromonas caviae as a junior objective synonym of A. punctata. This is important because the scientific community continues to use the name A. caviae almost exclusively instead of A. punctata. However, the corrective action of this Opinion will cause a new problem. A. punctata and A. eucrenophila will then become objective synonyms because both species will have the same type strain NCMB 74T, and A. punctata would have priority because it was published first (1890 vs. 1987). Thus, A. punctata rather than A. eucrenophila would become the correct name for DNA hybridization group 6. A. punctata has had a very confusing history since it was first described as Bacillus punctatus by Zimmermann in 1890. It was without a type strain for over 50 years, and unfortunately, has had an incorrect type strain for some 40 years. The name A. punctata as a bacterial species has been used incorrectly in the literature very frequently, either based on the wrong type strain or with the wrong definition or circumscription. The name A. punctata is not accepted or used by most specialists who study and publish scientific papers and reviews on Aeromonas. Under the heading 'Rejection of Names' Rule 56a of the Bacterial Code states reasons why the Judicial Commission can reject a name, the first is: '(1) An ambiguous name (nomen ambiguum), i.e., a name which has been used with different meanings and thus has become a source of error'. Rule 56a gives the Judicial Commission authority to place names on the list of rejected names. Our analysis of its history leads us to state unequivocally that A. punctata currently is, and has been throughout the vast majority of its history, an ambiguous name. After considering all the possible alternatives and their consequences we request the Judicial Commission to go against the rules of priority; to invoke case (1) of Rule 56a, and issue an Opinion conserving A. eucrenophila over A. punctata; and to place the name A. punctata on the list of rejected names. We argue that these actions will give instant stability to a complex and confusing situation by making A. eucrenophila rather than A. punctata the correct name for 'Aeromonas DNA hybridization group 6', an association that is almost universally accepted by the scientific community as reflected in the literature.

Workforce, Workload, and Burnout Among Intensivists and Advanced Practice Providers: A Narrative Review.

OBJECTIVES: To assess-by literature review and expert consensus-workforce, workload, and burnout considerations among intensivists and advanced practice providers. DESIGN: Data were synthesized from monthly expert consensus and literature review. SETTING: Workforce and Workload section workgroup of the Academic Leaders in Critical Care Medicine Task Force. MEASUREMENTS AND MAIN RESULTS: Multidisciplinary care teams led by intensivists are an essential component of critical care delivery. Advanced practice providers (nurse practitioners and physician assistants) are progressively being integrated into ICU practice models. The ever-increasing number of patients with complex, life-threatening diseases, concentration of ICU beds in few centralized hospitals, expansion of specialty ICU services, and desire for 24/7 availability have contributed to growing intensivist staffing concerns. Such staffing challenges may negatively impact practitioner wellness, team perception of care quality, time available for teaching, and length of stay when the patient to intensivist ratio is greater than or equal to 15. Enhanced team communication and reduction of practice variation are important factors for improved patient outcomes. A diverse workforce adds value and enrichment to the overall work environment. Formal succession planning for ICU leaders is crucial to the success of critical care organizations. Implementation of a continuous 24/7 ICU coverage care model in high-acuity, high-volume centers should be based on patient-centered outcomes. High levels of burnout syndrome are common among intensivists. Prospective analyses of interventions to decrease burnout within the ICU setting are limited. However, organizational interventions are felt to be more effective than those directed at individuals. CONCLUSIONS: Critical care workforce and staffing models are myriad and based on several factors including local culture and resources, ICU organization, and strategies to reduce burden on the ICU provider workforce. Prospective studies to assess and avoid the burnout syndrome among intensivists and advanced practice providers are needed.

Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities.

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory.

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch.

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1×10^{14} and 7.7×10^{14} electrons/cm^{3}. We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (<15 MV/m) and reach over 300 MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels.

Proton-driven plasma wakefield acceleration in AWAKE.

In this article, we briefly summarize the experiments performed during the first run of the Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal of AWAKE Run 1 (2013-2018) was to demonstrate that 10-20 MeV electrons can be accelerated to GeV energies in a plasma wakefield driven by a highly relativistic self-modulated proton bunch. We describe the experiment, outline the measurement concept and present first results. Last, we outline our plans for the future. This article is part of the Theo Murphy meeting issue 'Directions in particle beam-driven plasma wakefield acceleration'.

Exploring the role of the dental hygienist in reducing oral health disparities in Canada: A qualitative study.

OBJECTIVES: Reducing oral health disparities has been an ongoing challenge in Canada with the largest burden of oral disease exhibited in vulnerable populations, including Aboriginal people, the elderly, rural and remote residents, and newcomers. Dental hygienists are a unique set of professionals who work with and within communities, who have the potential to act as key change agents for improving the oral health of these populations. The purpose of this qualitative study was to explore, from the dental hygiene perspective, the role of dental hygienists in reducing oral health disparities in Canada. METHODS: Dental hygienists and key informants in dental hygiene were recruited, using purposeful and theoretical sampling, to participate in a non-directed, semi-structured one-on-one in-depth telephone interview using Skype and Call Recorder software. Corbin and Strauss's grounded theory methodology was employed with open, axial, and selective coding analysed on N-Vivo Qualitative software. RESULTS: The resulting theoretical framework outlines strategies proposed by participants to address oral health disparities; these included alternate delivery models, interprofessional collaboration, and increased scope of practice. Participants identified variation in dental care across Canada, public perceptions of oral health and dental hygiene practice, and lack of applied research on effective oral health interventions as challenges to implementing these strategies. CONCLUSION: The research confirmed the important role played by dental hygienists in reducing oral health disparities in Canada. However, due to the fragmentation of dental hygiene practice across Canada, a unified voice and cohesive action plan is needed in order for the profession to fully embrace their role.

Supervised toothbrushing programs in primary schools and early childhood settings: A scoping review.

OBJECTIVE: In this article we report the findings of a scoping review that aimed to identify and summarise the range of programs and guidelines available for toothbrushing programs in schools and early childhood settings. Dental caries is one of the most common preventable diseases affecting children worldwide. Untreated caries can impact on child health and wellbeing, development, socialisation and school attendance. Supervised toothbrushing programs in schools and other early childhood settings can be effective in improving the oral health of young children. There is limited understanding of the salient issues to consider when developing such programs or how they are best implemented in real world settings. METHODS: A scoping review methodology was utilised to provide a summary of the guidelines and programs available. Key search terms were developed, mapped and utilised to identify guidelines and programs across 6 databases and key search engines. RESULTS: We located 26 programs and guidelines that met the inclusion and exclusion criteria for the review. These were collated and summarised across key countries and critical aspects of program development and implementation were identified. Toothbrush type and storage, toothpaste strength and method of dispensing, toothbrush storage, staff training and parental consent are key considerations that varied widely. CONCLUSIONS AND RECOMMENDATIONS: Guidelines for supervised toothbrushing programs vary within and across countries due to differences in water fluoridation and availability of low fluoride toothpastes. The results of this review provide critical information to be considered when establishing and implementing toothbrushing programs in these settings.

Exploratory scoping of the literature on factors that influence oral health workforce planning and management in developing countries.

OBJECTIVES: The purpose of this study was to scope the literature that exists about factors influencing oral health workforce planning and management in developing countries (DCs). METHODS: The Arksey and O'Malley method for conducting a scoping review was used. A replicable search strategy was applied, using three databases. Factors influencing oral health workforce planning and management in DCs identified in the eligible articles were charted. FINDINGS: Four thousand citations were identified; 41 papers were included for review. Most included papers were situational analyses. Factors identified were as follows: lack of data, focus on the restorative rather than preventive care in practitioner education, recent increase in number of dental schools (mostly private) and dentistry students, privatization of dental care services which has little impact on care maldistribution, and debates about skill mix and scope of practice. Oral health workforce management in the eligible studies has a bias towards dentist-led systems. Due to a lack of country-specific oral health related data in developing or least developed countries (LDCs), oral health workforce planning often relies on data and modelling from other countries. DISCUSSION AND CONCLUSION: Approaches to oral health workforce management and planning in developing or LDCs are often characterized by approaches to increase numbers of dentists, thus not ameliorating maldistribution of service accessibility. Governments appear to be reducing support for public and preventative oral healthcare, favouring growth in privatized dental services. Changes to professional education are necessary to trigger a paradigm shift to the preventive approach and to improve relationships between different oral healthcare provider roles. This needs to be premised on greater appreciation of preventive care in health systems and funding models.

Perception of Nepalese dental hygiene and dentistry students towards the dental hygienists profession.

OBJECTIVES: This study investigates student and stakeholder perceptions of the role of the dental hygienist in Nepal. The impact of these perceptions on the professionalization of dental hygienists is described whilst exploring the consequences for oral health workforce planning. METHODS: Dentistry and dental hygiene students from one dental college in Nepal were asked to complete an anonymous questionnaire; 171 students returned the questionnaire containing a mix of forced response and open-ended items. Quantitative data were analysed using SPSS® 22. These data were complemented with qualitative information from survey open questions and from semi-structured interviews with key informants from several relevant organizations. Qualitative data were manually analysed and coded. Data were triangulated to contextualize quantitative data. RESULTS: A high level of positive regard for the role of the dental hygienist in Nepal was evident amongst dentistry and dental hygiene students in this college. Both groups believe that the dental hygienist can play a major role in raising oral health awareness in Nepal. The scope of practice of the dental hygienist was unclear with issues surrounding the scope of practice and reports of illegal practice by dental hygienists. Significant differences (P < 0.001) were noted between dental hygiene and dentistry students in relation to their opinion regarding independent practice and the need of supervision by a dentist. DISCUSSION AND CONCLUSION: Supervision of the dental hygienist by dentists and issues surrounding the scope of practice are polarizing the relationship between dentists, dental hygienists and the relevant professional organizations. This could hinder cooperation between these oral health professionals and might lead to underutilization of the dental hygienist. To improve the understanding about the roles of each oral health professional, establishing functional relationships and intraprofessional education involving dentistry and dental hygiene students needs to be introduced. This will benefit the introduction of preventative oral health services in Nepal. Government jobs and incentives to increase the retention and distribution of oral health professionals should be created. The government and professional organizations need to consider professionalizing the dental hygiene workforce and formalize the scope of practice. The unique demographic details of Nepal require a paradigm shift in oral health workforce management in Nepal.

Mechanical circulatory assist devices: a primer for critical care and emergency physicians.

Mechanical circulatory assist devices are now commonly used in the treatment of severe heart failure as bridges to cardiac transplant, as destination therapy for patients who are not transplant candidates, and as bridges to recovery and "decision-making". These devices, which can be used to support the left or right ventricles or both, restore circulation to the tissues, thereby improving organ function. Left ventricular assist devices (LVADs) are the most common support devices. To care for patients with these devices, health care providers in emergency departments (EDs) and intensive care units (ICUs) need to understand the physiology of the devices, the vocabulary of mechanical support, the types of complications patients may have, diagnostic techniques, and decision-making regarding treatment. Patients with LVADs who come to the ED or are admitted to the ICU usually have nonspecific clinical symptoms, most commonly shortness of breath, hypotension, anemia, chest pain, syncope, hemoptysis, gastrointestinal bleeding, jaundice, fever, oliguria and hematuria, altered mental status, headache, seizure, and back pain. Other patients are seen for cardiac arrest, psychiatric issues, sequelae of noncardiac surgery, and trauma. Although most patients have LVADs, some may have biventricular support devices or total artificial hearts. Involving a team of cardiac surgeons, perfusion experts, and heart-failure physicians, as well as ED and ICU physicians and nurses, is critical for managing treatment for these patients and for successful outcomes. This review is designed for critical care providers who may be the first to see these patients in the ED or ICU.