Practical quantum advantage in quantum simulation.

The development of quantum computing across several technologies and platforms has reached the point of having an advantage over classical computers for an artificial problem, a point known as 'quantum advantage'. As a next step along the development of this technology, it is now important to discuss 'practical quantum advantage', the point at which quantum devices will solve problems of practical interest that are not tractable for traditional supercomputers. Many of the most promising short-term applications of quantum computers fall under the umbrella of quantum simulation: modelling the quantum properties of microscopic particles that are directly relevant to modern materials science, high-energy physics and quantum chemistry. This would impact several important real-world applications, such as developing materials for batteries, industrial catalysis or nitrogen fixing. Much as aerodynamics can be studied either through simulations on a digital computer or in a wind tunnel, quantum simulation can be performed not only on future fault-tolerant digital quantum computers but also already today through special-purpose analogue quantum simulators. Here we overview the state of the art and future perspectives for quantum simulation, arguing that a first practical quantum advantage already exists in the case of specialized applications of analogue devices, and that fully digital devices open a full range of applications but require further development of fault-tolerant hardware. Hybrid digital-analogue devices that exist today already promise substantial flexibility in near-term applications.

Identifying a therapeutic target for vancomycin against staphylococci in young infants.

OBJECTIVES: To determine the therapeutic target of vancomycin in young infants with staphylococcal infections. METHODS: Retrospective data were collected for infants aged 0 to 90 days with CoNS or MRSA bacteraemia over a 4 year period at the Royal Children's Hospital Melbourne, Australia. Vancomycin broth microdilution MICs were determined. A published pharmacokinetic model was externally validated using the study dataset and a time-to-event (TTE) pharmacodynamic model developed to link the AUC of vancomycin with the event being the first negative blood culture. Simulations were performed to determine the trough vancomycin concentration that correlates with a 90% PTA of the target AUC24. RESULTS: Thirty infants, 28 with CoNS and 2 with MRSA bacteraemia, who had 165 vancomycin concentrations determined were included. The vancomycin broth microdilution MIC was determined for 24 CoNS and 1 MRSA isolate, both with a median MIC of 1 mg/L (CoNS range = 0.5-4.0). An AUC0-24 target of ≥300 mg/L·h or AUC24-48 of ≥424 mg/L·h. increased the chance of bacteriological cure by 7.8- and 7.3-fold, respectively. However, AUC0-24 performed best in the pharmacokinetic-pharmacodynamic model. This correlates with 24 to 48 h trough concentrations of >15-18 mg/L and >10-15 mg/L for 6- and 12-hourly dosing, respectively, and can be used to guide vancomycin therapy in this population. CONCLUSIONS: An AUC0-24 ≥300 mg/L·h or AUC24-48 ≥424 mg/L·h was associated with an increase in bacteriological cure in young infants with staphylococcal bloodstream infections.

Density Matrix Renormalization Group for Continuous Quantum Systems.

We introduce a versatile and practical framework for applying matrix product state techniques to continuous quantum systems. We divide space into multiple segments and generate continuous basis functions for the many-body state in each segment. By combining this mapping with existing numerical density matrix renormalization group routines, we show how one can accurately obtain the ground-state wave function, spatial correlations, and spatial entanglement entropy directly in the continuum. For a prototypical mesoscopic system of strongly interacting bosons we demonstrate faster convergence than standard grid-based discretization. We illustrate the power of our approach by studying a superfluid-insulator transition in an external potential. We outline how one can directly apply or generalize this technique to a wide variety of experimentally relevant problems across condensed matter physics and quantum field theory.

Risk factors for healthcare-associated infection among children in a low-and middle-income country.

BACKGROUND: Healthcare-associated infections (HAI) are one of significant causes of morbidity and mortality. Evaluating risk factors associated with HAI are important to improve clinical outcomes. We aimed to evaluate the risk factors of HAI in children in a low-to middle-income country. METHODS: A prospective cohort study was conducted during 43 months at a teaching hospital in Yogyakarta, Indonesia. All consecutive patients admitted to pediatric ICU and pediatric wards > 48 h were eligible. Those eligible patients were observed daily to identify the presence of HAI based on CDC criteria. The risk factors of HAI were identified. Multivariable logistic regression was used to identify independent risk factors. RESULTS: Total of 2612 patients were recruited. Of 467 were diagnosed as HAI. The cumulative incidence of HAI was 17.9%. In the multivariable analysis; length of stay > 7 days, severe sepsis, use of urine catheter, central venous catheter (CVC), non-standardized antibiotics, and aged < 1 year were independently associated with increased risk of HAI with adjusted OR (95%CI): 5.6 (4.3-7.3), 1.9 (1.3-2.9), 1.9 (1.3-2.6), 1.8 (1.1-2.9), 1.6 (1.2-2.0), and 1.4 (1.1-1.8), respectively. CONCLUSIONS: This study found that length of stay > 7 days, use of urine catheter and CVC, non-standardized antibiotic use, aged < 1 year, and had a diagnosis of severe sepsis increased risk of HAI.

Feasibility and acceptability of targeted salivary cytomegalovirus screening through universal newborn hearing screening.

AIM: This study aimed to determine the feasibility and parental acceptability of screening for congenital cytomegalovirus (cCMV) through saliva polymerase chain reaction in infants who did not pass their newborn hearing screening. Additionally, the utility (i.e. time to diagnosis and treatment) of this enhanced clinical pathway was evaluated. METHODS: The study was conducted through the Victorian Infant Hearing Screening Programme (VIHSP) across four maternity hospitals in Melbourne, Australia, during June 2019-March 2020. Parents were approached by VIHSP staff about obtaining a test for cytomegalovirus (CMV) at the time of their baby's second positive ('refer') result on the VIHSP screen. Participating parents collected a saliva swab for CMV polymerase chain reaction from their infants. Feasibility was determined by the proportion of 'referred' infants whose parents completed the salivary CMV screening test ≤21 days of life. Acceptability was measured through parent survey. RESULTS: Of 126 eligible families, 96 (76.0%) had salivary screening swabs taken ≤21 days of life. Most families (>92.0%) indicated that screening was acceptable, straightforward and thought testing their baby for cCMV was a good idea. One infant screened positive on day 30, was diagnosed with cCMV via confirmatory testing by day 31 and commenced valganciclovir on day 32. CONCLUSIONS: Obtaining a saliva sample to screen for cCMV in infants who do not pass their newborn hearing screen is feasible and appears acceptable to parents. This targeted cCMV screening method could be an option where mothers are rapidly discharged from hospital, especially in the context of the COVID-19 pandemic.

Deterministic Fast Scrambling with Neutral Atom Arrays.

Fast scramblers are dynamical quantum systems that produce many-body entanglement on a timescale that grows logarithmically with the system size N. We propose and investigate a family of deterministic, fast scrambling quantum circuits realizable in near-term experiments with arrays of neutral atoms. We show that three experimental tools-nearest-neighbor Rydberg interactions, global single-qubit rotations, and shuffling operations facilitated by an auxiliary tweezer array-are sufficient to generate nonlocal interaction graphs capable of scrambling quantum information using only O(logN) parallel applications of nearest-neighbor gates. These tools enable direct experimental access to fast scrambling dynamics in a highly controlled and programmable way and can be harnessed to produce highly entangled states with varied applications.

COVID-19 public health measures and respiratory viruses in children in Melbourne.

AIM: To describe the epidemiology of respiratory viruses in children before and during the 2020 SARS-CoV-2 pandemic and the relationship to public health measures instituted by the Victorian government. METHODS: Retrospective audit of respiratory viruses at a tertiary paediatric hospital in Melbourne from January 2015 up to week 47, 2020 in children under 18 years of age. The proportion of positive cases in weeks 1-47 in 2015-2019 (period 1) were compared to weeks 1-47, 2020 (period 2), and reviewed in the context of public health restrictions in Victoria. RESULTS: An annual average of 4636 tests were performed in period 1 compared to 3659 tests in period 2. Proportions of positive influenza A virus, influenza B virus, respiratory syncytial virus (RSV) and human parainfluenza virus were significantly reduced in period 2 compared to period 1: 77.3, 89.4, 68.6 and 66.9% reductions, respectively (all P < 0.001). From week 12-47, 2020, 28 893 SARS-CoV-2 tests were performed with a 0.64% positivity rate. Influenza viruses were not detected after week 17, RSV was not detected after week 35. CONCLUSIONS: Strict public health measures and border closures were successful in eliminating community transmission of SARS-CoV-2 in Melbourne. This was associated with a significant reduction in other respiratory virus infections in children. Identifying sustainable and effective ongoing public health interventions to reduce transmission of RSV and influenza could result in reduced morbidity and mortality in children and requires further research.

Collisionally Inhomogeneous Bose-Einstein Condensates with a Linear Interaction Gradient.

We study the evolution of a collisionally inhomogeneous matter wave in a spatial gradient of the interaction strength. Starting with a Bose-Einstein condensate with weak repulsive interactions in quasi-one-dimensional geometry, we monitor the evolution of a matter wave that simultaneously extends into spatial regions with attractive and repulsive interactions. We observe the formation and the decay of solitonlike density peaks, counterpropagating self-interfering wave packets, and the creation of cascades of solitons. The matter-wave dynamics is well reproduced in numerical simulations based on the nonpolynomial Schrödinger equation with three-body loss, allowing us to better understand the underlying behavior based on a wavelet transformation. Our analysis provides new understanding of collapse processes for solitons, and opens interesting connections to other nonlinear instabilities.

The hepatitis B birth-dose immunisation: Exploring parental refusal.

BACKGROUND: Hepatitis B virus (HBV) immunisation is the first vaccine of infant life and one of the most commonly refused immunisations on the Australian Immunisation Schedule. AIMS: To quantify the frequency of declined HBV immunisation birth-doses, investigate reasons for refusal, and determine information sources used by parents. MATERIALS AND METHODS: A cross-sectional study using a questionnaire was conducted on postnatal women who declined their newborn's HBV birth-dose immunisation during December 2016-July 2017 at an Australian tertiary referral hospital. Mothers who were non-English-speaking, unwell or medically unstable, or otherwise unavailable were excluded. RESULTS: One hundred and thirty-seven of the 1574 (8.7%) eligible reviewed infants had HBV immunisation birth-doses documented as declined; 113 mothers consented to complete the questionnaire. The most common reasons for declining the dose were: 'baby too young' (55.8%); preference for two, four and six-month HBV immunisations only (56.6%); perceived low risk of contracting HBV (45.1%); and a fear of 'overloading' their baby's immune system (42.5%). General practitioners or nurses/midwives (43.3%) and the internet/media (33.6%) were the predominant information sources consulted, and 58.4% felt satisfied with the information they received antenatally. Eighty-eight of 113 mothers (77.9%) would still consider future immunisations for their infant. CONCLUSIONS: The majority of postnatal women decline HBV birth-dose immunisation for their newborns citing age-related safety concerns and vaccine misconceptions. Informal information sources such as the internet and media are often consulted. Addressing the need for antenatal and health professional education toward the birth-dose may be instrumental in improving uptake.

Controlling Quantum Transport via Dissipation Engineering.

Inspired by the microscopic control over dissipative processes in quantum optics and cold atoms, we develop an open-system framework to study dissipative control of transport in strongly interacting fermionic systems, relevant for both solid-state and cold-atom experiments. We show how subgap currents exhibiting multiple Andreev reflections-the stimulated transport of electrons in the presence of Cooper pairs-can be controlled via engineering of superconducting leads or superfluid atomic gases. Our approach incorporates dissipation within the channel, which is naturally occurring and can be engineered in cold gas experiments. This opens opportunities for engineering many phenomena with transport in strongly interacting systems. As examples, we consider particle loss and dephasing, and note different behavior for currents with different microscopic origin. We also show how to induce nonreciprocal electron and Cooper-pair currents.

Spin Models, Dynamics, and Criticality with Atoms in Tilted Optical Superlattices.

We show that atoms in tilted optical superlattices provide a platform for exploring coupled spin chains of forms that are not present in other systems. In particular, using a period-2 superlattice in one dimension, we show that coupled Ising spin chains with XZ and ZZ spin coupling terms can be engineered. We use optimized tensor network techniques to explore the criticality and nonequilibrium dynamics in these models, finding a tricritical Ising point in regimes that are accessible in current experiments. These setups are ideal for studying low-entropy physics, as initial entropy is "frozen-out" in realizing the spin models, and provide an example of the complex critical behavior that can arise from interaction-projected models.

Treelike Interactions and Fast Scrambling with Cold Atoms.

We propose an experimentally realizable quantum spin model that exhibits fast scrambling, based on nonlocal interactions that couple sites whose separation is a power of 2. By controlling the relative strengths of deterministic, nonrandom couplings, we can continuously tune from the linear geometry of a nearest-neighbor spin chain to an ultrametric geometry in which the effective distance between spins is governed by their positions on a tree graph. The transition in geometry can be observed in quench dynamics, and is furthermore manifest in calculations of the entanglement entropy. Between the linear and treelike regimes, we find a peak in entanglement and exponentially fast spreading of quantum information across the system. Our proposed implementation, harnessing photon-mediated interactions among cold atoms in an optical cavity, offers a test case for experimentally observing the emergent geometry of a quantum many-body system.

Excitation Modes of Bright Matter-Wave Solitons.

We experimentally study the excitation modes of bright matter-wave solitons in a quasi-one-dimensional geometry. The solitons are created by quenching the interactions of a Bose-Einstein condensate of cesium atoms from repulsive to attractive in combination with a rapid reduction of the longitudinal confinement. A deliberate mismatch of quench parameters allows for the excitation of breathing modes of the emerging soliton and for the determination of its breathing frequency as a function of atom number and confinement. In addition, we observe signatures of higher-order solitons and the splitting of the wave packet after the quench. Our experimental results are compared to analytical predictions and to numerical simulations of the one-dimensional Gross-Pitaevskii equation.

Compliance with screening for and recommended management of maternal group B streptococcus carriage in pregnancy.

BACKGROUND: Universal screening of pregnant women at 35-37 weeks gestation is recommended for detection of anogenital group B streptococcus carriage. Intrapartum chemoprophylaxis is prescribed to carriers to prevent transmission to babies, reducing early-onset neonatal group B streptococcal sepsis. AIMS: To review compliance with, and the effects of education on group B streptococcus screening and intrapartum chemoprophylaxis practices at The Royal Women's Hospital, Melbourne, Australia. MATERIALS AND METHODS: A retrospective audit of women delivering in February 2016 and February-March 2017 was conducted. In February 2017, updated early-onset group B streptococcal disease prevention guidelines were released and promoted with targeted education of clinical staff. Compliance was considered appropriate if practices followed up-to-date local protocols. RESULTS: Screening rate for group B streptococcus was 84.4% (599/710) and carriage rate 19.5% (109/558), while intrapartum antibiotic prophylaxis was optimal in 83% of those labouring greater than four hours (39/47). There was no significant difference in compliance between 2016 and 2017. Of 113 women with unknown group B streptococcal status at delivery, only five of 33 (15%) with clinical risk factors for early-onset neonatal disease received intrapartum prophylaxis. CONCLUSIONS: Compliance remained stable, with no change during or after implementation of new protocols. Compliance with protocols was low for cases with unknown group B streptococcal status at delivery but with the presence of one or more clinical risk factors for early-onset group B streptococcal sepsis.

True Pathogen or Contamination: Validation of Blood Cultures for the Diagnosis of Nosocomial Infections in a Developing Country.

Background: Blood culture results are frequently used to guide antibiotic decision-making, but culture contaminants need to be distinguished from true pathogens. Aims: To assess the contamination rate of blood cultures and validate a method to distinguish between true bacteraemia and contamination. Methods: We analysed blood culture results from children who were admitted to the paediatric ICU and paediatric wards at the Sardjito Hospital, Yogyakarta, Indonesia between December 2010 and February 2013. For each positive culture result, the type of isolated organism, time to positivity, and the number of positive culture sites were considered to classify the isolate as representing a true bacteraemia or contaminant. Results: There were 1293 cultures obtained from blood and 308 (23.8%) were positive for bacterial growth. Fifty-three (4.1%) of the total cultures drawn fulfilled criteria for contaminants. The most common blood culture contaminants were coagulase-negative staphylococci. Conclusion: Using standardized criteria, it is possible to implement a working method to identify true nosocomial infection from blood culture contaminant, and thus limit the effect of contaminated blood culture on irrational antibiotic use.

Manipulating the baby biome: What are the issues?

Establishing a baby biome through the controversial practice of 'vaginal seeding' has generated interest among the general public and healthcare providers alike. We discuss the potential risks of this practice and offer a harm minimisation approach to managing women requesting vaginal microbiome transfer after delivery by caesarean section.

Evaluating an admission avoidance pathway for children in the emergency department: outpatient intravenous antibiotics for moderate/severe cellulitis.

OBJECTIVE: Children with moderate/severe cellulitis requiring intravenous antibiotics are usually admitted to hospital. Admission avoidance is attractive but there are few data in children. We implemented a new pathway for children to be treated with intravenous antibiotics at home and aimed to describe the characteristics of patients treated on this pathway and in hospital and to evaluate the outcomes. METHODS: This is a prospective, observational cohort study of children aged 6 months-18 years attending the ED with uncomplicated moderate/severe cellulitis in March 2014-January 2015. Patients received either intravenous ceftriaxone at home or intravenous flucloxacillin in hospital based on physician discretion. Primary outcome was treatment failure defined as antibiotic change within 48 hours due to inadequate clinical improvement or serious adverse events. Secondary outcomes include duration of intravenous antibiotics and complications. RESULTS: 115 children were included: 47 (41%) in the home group and 68 (59%) in the hospital group (59 hospital-only, 9 transferred home during treatment). The groups had similar clinical features. 2/47 (4%) of the children in the home group compared with 8/59 (14%) in the hospital group had treatment failure (P=0.10). Duration of intravenous antibiotics (median 1.9 vs 1.8 days, P=0.31) and complications (6% vs 10%, P=0.49) were no different between groups. Home treatment costs less, averaging $A1166 (£705) per episode compared with $A2594 (£1570) in hospital. CONCLUSIONS: Children with uncomplicated cellulitis may be able to avoid hospital admission via a home intravenous pathway. This approach has the potential to provide cost and other benefits of home treatment.

ANTIBIOTIC RESISTANCE AND MORTALITY IN CHILDREN WITH NOSOCOMIAL BLOODSTREAM INFECTION IN A TEACHING HOSPITAL IN INDONESIA.

Nosocomial infection is a major problem in hospitals worldwide. Understanding patterns of bacterial etiology and antibiotic susceptibility are important factors to combating nosocomial infection. Among children with nosocomial bloodstream infection (BSI), we identified pathogens and determined antibiotics resistance patterns and mortality rates for antibiotic-susceptible and multidrugresistant (MDR) infection in patients with nosocomial BSI in pediatric wards and PICU at Dr Sardjito Hospital, Indonesia during December 2010 to February 2013. Of 174 isolates from 170 patients, 168 pathogens were bacteria, of which 148 were gram-negative. Pseudomonas aeruginosa, Klebsiella spp, Enterobacteriaceae, Acinetobacter baumanii, and Escherichia coli was found in 55%, 6%, 4%, 1%, and <1%, respectively of the isolates. Imipenem, amikacin, ciprofloxacin, and ceftazadime had the highest sensitivity to nosocomial pathogens at 86%, 84%, 84%, and 75%, respectively. Eleven patients had MDR-infections, 7 of whom died. Among 153 patients infected with bacteria resistant to <3 classes of antibiotics (non-MDR), mortality was 40%, and among 4 patients with fully drug-susceptible sepsis only one died. Thus, substantial mortality was observed in children with nosocomial-BSI, particularly with MDR pathogens. Given the further high risk of resistance with wider use of carbapenems, third generation cephalosporins and flouroquinolones, prevention should be given highest priority in combating hospital-acquired infection.

Bacteremia and pneumonia in a tertiary PICU: an 11-year study.

OBJECTIVES: To describe trends in aetiology and resistance patterns and patient outcomes of bacteraemia and pneumonia in a PICU over an 11-year period. We also describe interventions aimed at reducing multi-resistant infections and other serious bacterial infections in the PICU. DESIGN AND SETTING: This cohort study involved data collected between January 2002 and December 2012 in the PICU of the Royal Children's Hospital in Melbourne, Australia. We documented all bacterial and fungal pathogens isolated from culture of blood or bronchial alveolar lavage fluid. Trends in aetiology and antibiotic resistance patterns were evaluated, as well as the case fatality rates of population-subgroups. PATIENTS, MEASUREMENT AND MAIN RESULTS: Overall, 881 patients (8.9%) had 1,480 serious bacterial or fungal infections and 1.2% of the PICU population suffered a multidrug-resistant infection. Twenty-six percent of 597 total deaths in the PICU during that time period were associated with a serious bacterial infection of the blood or lungs. Children in PICU with a serious infection in blood or lungs had a case fatality rate of 17.5% (95% CI, 15.0-20.2), compared with children overall in the PICU with a case fatality rate of 6.0% (95% CI, 5.5-6.5). The case fatality rate among children with multidrug-resistant sepsis was 25.6% (95% CI, 18.1-34.4) and among children with a persistent or recurrent infection in blood or lungs was 43.1% (95% CI, 30.8-56.0). Cases of multidrug-resistant bacteremia and bronchial alveolar lavage-proven pneumonia increased from 2002 to 2010 and significantly decreased from 2011, coinciding with improvements in antibiotic stewardship and infection control. CONCLUSIONS: Multiresistant bacterial sepsis and persistent or recurrent sepsis are major threats in pediatric intensive care and are associated with disproportionally high death rates. Our study describes a model for monitoring these serious infections and the effects of infection control interventions in the PICU.