Impact of the B.1.1.7 variant on neutralizing monoclonal antibodies recognizing diverse epitopes on SARS-CoV-2 Spike

The interaction of the SARS-CoV-2 Spike receptor binding domain (RBD) with the ACE2 receptor on host cells is essential for viral entry. RBD is the dominant target for neutralizing antibodies and several neutralizing epitopes on RBD have been molecularly characterized. Analysis of circulating SARS-CoV-2 variants has revealed mutations arising in the RBD, the N-terminal domain (NTD) and S2 subunits of Spike. To fully understand how these mutations affect the antigenicity of Spike, we have isolated and characterized neutralizing antibodies targeting epitopes beyond the already identified RBD epitopes. Using recombinant Spike as a sorting bait, we isolated >100 Spike-reactive monoclonal antibodies from SARS-CoV-2 infected individuals. ≈45% showed neutralizing activity of which ≈20% were NTD-specific. None of the S2-specific antibodies showed neutralizing activity. Competition ELISA revealed that NTD-specific mAbs formed two distinct groups: the first group was highly potent against infectious virus, whereas the second was less potent and displayed glycan-dependant neutralization activity. Importantly, mutations present in B.1.1.7 Spike frequently conferred resistance to neutralization by the NTD-specific neutralizing antibodies. This work demonstrates that neutralizing antibodies targeting subdominant epitopes need to be considered when investigating antigenic drift in emerging variants.

HIV-1 Vpr antagonizes innate immune activation by targeting karyopherin-mediated NF-κB/IRF3 nuclear transport

HIV-1 must replicate in cells that are equipped to defend themselves from infection through intracellular innate immune systems. HIV-1 evades innate immune sensing through encapsidated DNA synthesis and encodes accessory genes that antagonize specific antiviral effectors. Here, we show that both particle associated, and expressed HIV-1 Vpr, antagonize the stimulatory effect of a variety of pathogen associated molecular patterns by inhibiting IRF3 and NF-κB nuclear transport. Phosphorylation of IRF3 at S396, but not S386, was also inhibited. We propose that, rather than promoting HIV-1 nuclear import, Vpr interacts with karyopherins to disturb their import of IRF3 and NF-κB to promote replication in macrophages. Concordantly, we demonstrate Vpr-dependent rescue of HIV-1 replication in human macrophages from inhibition by cGAMP, the product of activated cGAS. We propose a model that unifies Vpr manipulation of nuclear import and inhibition of innate immune activation to promote HIV-1 replication and transmission.

Strengthening core competences of medical and public health students for public health emergencies

Background

The importance of public health capacity development with a focus on public health emergencies and humanitarian assistance is continuously increasing at the global scale. In the time of Public Health Emergencies of International Concern is crucial to provide basic training in core public health competences to all health professionals, including students. Faculty of Medicine & Dentistry, Palacký University Olomouc, Czech Republic (full ASPHER member), implemented in medical as well as public health curricula new topics focused on core competences of health professionals in the area of public health emergencies and humanitarian assistance.

Objectives

To strengthen competences and skills of medical as well as public health students to prepare them better for public health emergencies and humanitarian assistance in the time of increasing risk of global public health emergencies. New modules were proposed and tested in all education programmes at our Faculty of Medicine & Dentistry, Palacký University Olomouc (CZ): General Medicine (Czech and English programmes), Dentistry (Czech and English programmes) and Public Health (Czech programme).

Results

New modules on Public Health Emergencies, including preparedness, responses, risk management and risk communication were successfully tested in all education programmes during the academic year 2018/19 and fully implemented for the academic year 2019/20. New module has blended learning structure based on combination of face-to-face seminars and exercises with e-learning parts, including self-assessment. New module is presented in details.

Conclusions

This new education module fully supports international recommendations to strengthen public health competences and skills of medical as well as public health students to be ready for any unexpected public health emergencies at all levels, in particular at the local community level. COVID-19 pandemic confirmed.

Supported by university project CZ.02.69/0.0/16_015/0002337

Key messages

Medical and public health students with competences and skills on public health emergencies and humanitarian assistance will be an asset for any public health emergency of international concern.

New education module on public health emergencies will support both medical and public health students to be prepared for risk communication, advocacy and action if needed and called to action.

Review of pandemic plans, varying international approaches focusing on medical students’ contribution

A review of pandemic plans and international approaches to pandemics focusing on the responsibilities of medical students should they be called to help in times of need. Are there specific guidelines or competencies in place with respect to medical students? Are medical students being utilised to their maximal capability when compared across different nations on an international basis? These questions were kept in mind during the evaluation and analysis of publicly available pandemic plans and other international systems concerning the approach to pandemics. The main differences, strengths and weaknesses of these responses will be highlighted. The presentation will conclude with proposals of the specific role medical students could play in the pandemic response and the importance of their contribution on an international level.

Future visions for medical education, the importance of public health themes in education and beyond

Steps for the future improvement of competencies evaluation and fulfilment were studied, with the eventual goal of the unification of guidelines internationally to ensure the standardisation and uniformity of the quality of medical education. The future vision for the integration of public health into medical education curriculums, highlighting the importance of public health in medical education and its application in a wide variety of situations across medical education and beyond in practise as a medical professional in a range of specialities. The need for ways to increase engagement of medical students within public health issues will also be discussed.

Personal experiences of medical school education: methods to evaluate competency and ways to improve

Personal experiences of medical school education and the manner in which it is delivered will be discussed. Examples of approaches used for student evaluation of different competencies and the methods to track their progress and development were identified. They were appraised, with their strengths and weaknesses discussed. Ideas to improve the approaches for competencies assessment in medical students were also explored.

Comparing European guidelines for medical student education focusing on emergency preparedness

A review of a variety of European guidelines for the assessment of medical students and their education, progression and preparedness for practise post-medical school. The various approaches were compared and contrasted with the advantages and disadvantages of each being evaluated. Their approaches towards emergency situation preparedness, or lack thereof, were also assessed.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Implementing Mycoplasma genitalium testing across a London-based sexual health service: A quality improvement project

Recent national guidelines recommended testing for Mycoplasma genitalium (MG) in clinically-indicated conditions (CIC) including non-gonococcal urethritis (NGU), pelvic inflammatory disease (PID) and epididymo-orchitis. Over five months in 2018 a quality improvement project (QIP) was carried out across three London sexual health clinics with the aim of increasing MG testing rates in CICs. Three Plan-Do-Study-Act (PDSA) cycles were completed: improving IT access, an education event and reminder emails for clinicians who did not test in CIC. To measure testing rates ten patients from each CIC were randomly selected each week and MG testing outcomes were collected. As a balancing measure, we identified the rate of inappropriate MG testing. MG testing rates in patients with NGU increased to 90% following QIP initiation (baseline rate 60%) and this increase was sustained. No increase in MG testing was seen in PID and epididymo-orchitis. Inappropriate MG test rates were high (median of 11%) but remained constant throughout the QIP period. As MG testing is expanding across the UK, we outline a QIP integrating MG testing into a busy multi-site, sexual health service improving testing uptake while not increasing inappropriate testing.

P275 Uncontrolled post-clinic blood pressure readings can identify nocturnal non-dipping blood pressure pattern

Funding Acknowledgements

Aga Khan University Faculty of Health Sciences Research Committee (#80096)

On Behalf

PC BP (Post Clinic Blood Pressure) Study Group

Background

Nocturnal non-dipping increases cardiovascular morbidity and mortality in both hypertensive and normotensive subjects. Ambulatory blood pressure monitoring(ABPM) can identify nocturnal blood pressure(BP) dipping patterns but clinic BP cannot. We previously showed that 15-minute post-clinic BP correlates well with 24- hour ABPM.

Purpose

We aimed to determine if 15-minute post-clinic BP reading helped to identify patients with nocturnal non-dipping pattern.

Methods

A cross-sectional study involving 150 participants, as part of the Post Clinic-Ambulatory Blood Pressure(PC-ABP) study, was conducted in cardiology clinics. Participants aged ≥18 years, with hypertension or those referred for its assessment, were included. Pregnant females were excluded. Post-clinic BP was taken 15 minutes after the patient-physician encounter in the clinic using an automated, validated BP device by a research assistant. All the participants were then referred for 24-hour ABPM. Patterns of nocturnal dipping were studied amongst groups of controlled(<140 mmHg) and uncontrolled(≥140mmHg) post-clinic systolic BP(SBP). Fischer exact test was used to determine the difference in dipping patterns amongst the two groups.

Results

The mean age of participants was 60.3 ± 11.9 years. Of 150 participants, 49% were male and of all, 76% were hypertensive. Mean nighttime SBP(±SD) was 121.9(±18) mmHg(p-value <0.001). Mean nighttime DBP(±SD) was 68.7(± 8.7) mmHg(p < 0.001). Patterns of nocturnal dipping amongst patients with mean post-clinic SBP <140mmHg versus ≥140mmHg has been shown in Table 1. The difference in nocturnal dipping patterns between the two groups was statistically insignificant(p-value 0.071). Pearson correlation coefficient between post-clinic SBP and nighttime SBP for patients with loss of dip was higher (0.64; p < 0.001) whereas it was 0.56(p-value <0.001) for those with preserved dip. 

Conclusion

Uncontrolled post-clinic BP can help in identifying patients with nocturnal non-dipping. Larger studies can help determine the prognostic value of post-clinic BP amongst patients with nocturnal non-dipping.

Nocturnal Dipping Amongst The Two Groups Controlled PC SBP <140mmHg (n = 80) Uncontrolled PC SBP ≥140mmHg (n = 70) Preserved Nocturnal Dipping (10 to 20% nocturnal drop in SBP) 61.2% (n = 49) 47.1% (n = 33) Loss of Dip (>0% to <10% of nocturnal drop in SBP) 33.8% (n = 27) 48.6% (n = 34) Reversed Dip (≤0% drop in SBP) 5% (n = 4) 1.4%(n = 1) Excessive Dip (>20% drop in SBP) 0 2.9% (n = 2) Table 1 shows the patterns of nocturnal dipping amongst patients with controlled (<140mmHg) and uncontrolled (≥140mmHg) 15-minute post-clinic systolic blood pressure (PC SBP).

Sensitivity of larval and juvenile freshwater mussels (unionidae) to ammonia, chloride, copper, potassium, and selected binary chemical mixtures

In aquatic environments, organisms such as freshwater mussels are likely exposed to complex contaminant mixtures related to industrial, agricultural, and urban activities. With growing interest in understanding the risk that chemical mixtures pose to mussels, this investigation focused on the effects of various waterborne contaminants (ammonia, chloride, copper, and potassium) and selected binary mixtures of these chemicals following a fixed-ratio design to Villosa iris glochidia and juvenile Lampsilis fasciola. In individual exposures, 48-h EC₅₀ values were determined for V. iris glochidia exposed to ammonia chloride (7.4 [95% confidence interval (CI) 6.6-8.2] mg N/L), ammonia sulfate (8.4 [7.6-9.1] mg N/L), copper sulfate (14.2 [12.9-15.4] μg Cu²⁺/L), potassium chloride (12.8 [11.9-13.7] mg K⁺/L), potassium sulfate (10.1 [8.9-11.2] mg K⁺/L), and sodium chloride (480.5 [435.5-525.5] mg Cl^-/L). The 7-d LC₅₀ values for juvenile L. fasciola were determined for potassium sulfate (45.0 [18.8-71.2] mg K⁺/L), and sodium chloride (1738.2 [1418.6-2057.8] mg Cl^-/L). In Ontario these waterborne contaminants have been reported to co-occur, with concentrations exceeding the EC₁₀ for both life stages at some locations. Data from binary mixture exposures for V. iris glochidia (chloride-ammonia, chloride-copper, and copper-ammonia) and juvenile L. fasciola (chloride-potassium) were analyzed using a regression-based, dose-response mixture analysis modeling framework. Results from the mixture analysis were used to determine if an additive model for mixture toxicity [concentration addition (CA) or independent action (IA)] best described the toxicity of each mixture and if deviation towards dose-ratio (DR) or dose-level (DL) synergism/antagonism (S/A) occurred. For all glochidia binary mixture exposures, CA was the best fit model with DL deviation reported for the chloride-copper mixture and DR deviation reported for the copper-ammonia mixture. Using the model deviation ratio (MDR), the observed toxicity in all three glochidia mixture exposures were adequately described by both CA (mean = 0.71) and IA (mean = 0.97) whereas the juvenile mixture exposure was only adequately described by CA (mean = 0.64; IA mean = 0.05).

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star-black hole, and binary black hole systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. During O3, the median localization volume (90% credible region) is expected to be on the order of 10 5 , 10 6 , 10 7 Mpc 3 for binary neutron star, neutron star-black hole, and binary black hole systems, respectively. The localization volume in O4 is expected to be about a factor two smaller than in O3. We predict a detection count of 1 - 1 + 12 ( 10 - 10 + 52 ) for binary neutron star mergers, of 0 - 0 + 19 ( 1 - 1 + 91 ) for neutron star-black hole mergers, and 17 - 11 + 22 ( 79 - 44 + 89 ) for binary black hole mergers in a one-calendar-year observing run of the HLV network during O3 (HLVK network during O4). We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers.

P274 Three-hour ambulatory blood pressure monitoring: a new surrogate for ambulatory blood pressure assessment in the pakistani population

Funding Acknowledgements

Aga Khan University Faculty of Health Sciences Research Committee (#80096)

On Behalf

PC BP (Post Clinic Blood Pressure) Study Group

Background

The gold standard Ambulatory Blood Pressure Monitoring (ABPM) eliminates white coat effect. However, it is expensive and 24 hours long, making it cumbersome. Prior studies in other populations have investigated the utility of shorter intervals in which ABPM can be used to get the same results as 24-hour ABPM.

Purpose

Our objective was to determine if 3-hour ABPM correlates with 24-hour ABPM in the Pakistani population.

Methods

A cross-sectional study, involving 150 participants as part of the PC ABP (post clinic ambulatory blood pressure) study, was conducted in the cardiology clinics, starting 2015. Participants ≥18years of age and were either hypertensive or referred for assessment of hypertension were included. Pregnant females were excluded. Blood pressure (BP) readings were taken with an ambulatory BP monitor over a 24 hour period, every half hour during daytime and every hour during nighttime. After excluding the first hour called the white-coat window, the mean of the first 6 systolic readings taken every half hour during the daytime was calculated and was called systolic 3-hour ABPM. Pearson correlation coefficients were calculated and Bland Altman plots were constructed to determine the correlation and limits of agreement between mean systolic 3-hour ABPM and mean daytime ABPM.

Results

Of 150 participants, 49% were male.  Of all participants, 76% were hypertensive. Mean age of the participants was 60.3 ± 11.9 years. Mean systolic 3-hour ABPM was 135.0 ± 16mmHg. Mean systolic daytime ABPM was 134.7 ± 15mmHg respectively. Pearson correlation coefficient between mean systolic 3-hour ABPM and mean systolic daytime ABPM was 0.85 (p-value of <0.001). The difference between systolic 3-hour ABPM and systolic daytime ABPM was 0.3mmHg (95% Confidence Interval -1.1 to 1.7mmHg). The limits of agreement were 18mmHg to -17mmHg for systolic 3-hour ABPM and systolic daytime ABPM.

Conclusion

Three-hour ABPM correlates well with 24-hour gold standard ABPM in the Pakistani population. We suggest using this shortened study for the assessment of hypertension where a full ABPM cannot be conducted due to expense or logistic reasons, thus saving time and upfront cost.

ASPHER V4 Working Group supports the road map for professionalising the public health workforce

Background

The ASPHER V4 Working Group (WG) was established in 2016 and officially launched during the 9th European Public Health Conference in Vienna. One of the key objectives of the WG is to strengthen public health capacity development in V4 countries. The WG supports the implementation of the recently reviewed European Action Plan for Strengthening Public Health Capacities (EAP). The EAP’s review highlighted the need to focus further action on four enabling Essential Public Health Functions (EPHOs) including human resources for public health. This is why the WG is heavily involved in the recent development of a new Road map for professionalising the public health workforce, one of the products of the recently established Coalition of Partners (CoP) that was convened by the WHO Regional Office for Europe in close cooperation with ASPHER and Maastricht University.

Objectives

Supporting the WHO CoP with a focus on development and further implementation of a new Road map for professionalising public health workforce in V4 countries. Using a new rapid assessment tool to evaluate the state of the public health profession in the Czech Republic. Sharing the report on the current state of public health professions in the Czech Republic with the WG and using it as a comparison of the current state in all V4 countries.

Results

Key strengths and weaknesses of the first rapid assessment of the current state of the public health profession in the Czech Republic are presented. Key actions are proposed for the WG: a) Preparation of a grant proposal to the International V4 Fund and b) Continuing active involvement in CoP activities.

Conclusions

The rapid assessment tool for evaluating the state of the public health profession was successfully implemented in the Czech Republic with the close cooperation of academia, researchers, policy makers and practitioners. The summary confirms that further work on the professionalization of the public health workforce is needed.

Key messages

ASPHER V4 WG is strongly involved in the development of a new road map for professionalising the public health workforce, coordinated by the WHO CoP, ASPHER and Maastricht University. Summary of the first rapid assessment of the current state of the public health profession in the Czech Republic confirms the importance of further action in this area of work.

P2831Safety of atrial fibrillation catheter ablation in the elderly

Background

Catheter ablation for drug refractory, symptomatic atrial fibrillation (AF), is becoming increasingly common and can be beneficial in alleviating symptoms. However, in the elderly, there are concerns about the risks an invasive procedure poses, with limited published data available in those aged over 80 years.

Purpose

To determine the complication risk of AF catheter ablation in the elderly

Methods

Complications were identified from patient records in 3156 consecutive patients who underwent radiofrequency catheter ablation for AF, at a tertiary cardiology centre between 2013–2017. All cases were performed under general anesthesia.

Results

In this cohort of 3156 patients (mean age= 62.9±11.0 years, female = 29.9%), 90 (2.85%) (mean age= 66±10.0 years, female = 49.5%) complications were identified. In patients aged ≥80 years, complications occurred in 5 out of 99 patients (5.05%) (mean age= 82.6±1.2, female=100%), compared to 85 out of 3057 patients (2.78%) in those aged <80 years (mean age= 65±10.3, female = 49.4%). The difference was not significant p=0.18. Complications in the elderly all occurred acutely, and included groin haematoma (2.02%), pneumonia (2.02%) and pericardial effusion (1.01%).

Conclusion

Catheter ablation for AF in patients ≥80 years of age, is not associated with a significant increase in complication risk, compared to those who are younger.

Tests of General Relativity with GW170817

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due to large extra dimensions. Finally, the polarization content of the gravitational wave signal is studied. The results of all tests performed here show good agreement with GR.

Entropy generation and activation energy mechanism in nonlinear radiative flow of Sisko nanofluid: rotating disk

The theme of the present communication is to explore the novel analysis of entropy generation optimization, binary chemical reaction and activation energy for nonlinear convective flow of Sisko model on a radially stretchable rotating disk in the presence of a uniform vertical magnetic field. Nonlinear mixed convection, nonlinear thermal radiation, MHD, viscous dissipation, Joule heating and non-uniform heat generation/absorption are also considered. Nanofluid model includes significant slip mechanism of Brownian motion and thermophoresis. Apposite transformations are endorsed to get the nonlinear coupled ODEs system. The resultant system of ordinary differential equations is endeavoured for series solutions through homotopic technique. Total entropy generation is inspected through numerous emerging flow variables. Comparative study is made for temperature, velocity, heat transfer rate, Bejan number, entropy generation and mass transfer Nusselt number by considering shear thickening and thinning fluids. Finally, a comparison is specified with the previous existing results.

Constraining the p-Mode-g-Mode Tidal Instability with GW170817

We analyze the impact of a proposed tidal instability coupling p modes and g modes within neutron stars on GW170817. This nonresonant instability transfers energy from the orbit of the binary to internal modes of the stars, accelerating the gravitational-wave driven inspiral. We model the impact of this instability on the phasing of the gravitational wave signal using three parameters per star: an overall amplitude, a saturation frequency, and a spectral index. Incorporating these additional parameters, we compute the Bayes factor (lnB_{!pg}^{pg}) comparing our p-g model to a standard one. We find that the observed signal is consistent with waveform models that neglect p-g effects, with lnB_{!pg}^{pg}=0.03_{-0.58}^{+0.70} (maximum a posteriori and 90% credible region). By injecting simulated signals that do not include p-g effects and recovering them with the p-g model, we show that there is a ≃50% probability of obtaining similar lnB_{!pg}^{pg} even when p-g effects are absent. We find that the p-g amplitude for 1.4  M_{⊙} neutron stars is constrained to less than a few tenths of the theoretical maximum, with maxima a posteriori near one-tenth this maximum and p-g saturation frequency ∼70  Hz. This suggests that there are less than a few hundred excited modes, assuming they all saturate by wave breaking. For comparison, theoretical upper bounds suggest ≲10^{3} modes saturate by wave breaking. Thus, the measured constraints only rule out extreme values of the p-g parameters. They also imply that the instability dissipates ≲10^{51}  erg over the entire inspiral, i.e., less than a few percent of the energy radiated as gravitational waves.

Search for Subsolar-Mass Ultracompact Binaries in Advanced LIGO's First Observing Run

We present the first Advanced LIGO and Advanced Virgo search for ultracompact binary systems with component masses between 0.2  M_{⊙}-1.0  M_{⊙} using data taken between September 12, 2015 and January 19, 2016. We find no viable gravitational wave candidates. Our null result constrains the coalescence rate of monochromatic (delta function) distributions of nonspinning (0.2  M_{⊙}, 0.2  M_{⊙}) ultracompact binaries to be less than 1.0×10^{6}  Gpc^{-3}  yr^{-1} and the coalescence rate of a similar distribution of (1.0  M_{⊙}, 1.0  M_{⊙}) ultracompact binaries to be less than 1.9×10^{4}  Gpc^{-3}  yr^{-1} (at 90% confidence). Neither black holes nor neutron stars are expected to form below ∼1  M_{⊙} through conventional stellar evolution, though it has been proposed that similarly low mass black holes could be formed primordially through density fluctuations in the early Universe and contribute to the dark matter density. The interpretation of our constraints in the primordial black hole dark matter paradigm is highly model dependent; however, under a particular primordial black hole binary formation scenario we constrain monochromatic primordial black hole populations of 0.2  M_{⊙} to be less than 33% of the total dark matter density and monochromatic populations of 1.0  M_{⊙} to be less than 5% of the dark matter density. The latter strengthens the presently placed bounds from microlensing surveys of massive compact halo objects (MACHOs) provided by the MACHO and EROS Collaborations.

Imaging quantum fluctuations near criticality

A quantum phase transition (QPT) occurs between two competing phases of matter at zero temperature, driven by quantum fluctuations. Though the presence of these fluctuations is well established, they have not been locally imaged in space and their local dynamics has not been studied so far. We use a scanning superconducting quantum interference device to image quantum fluctuations in the vicinity of the QPT from a superconductor to an insulator. We find fluctuations of the diamagnetic response in both space and time that survive well below the transition temperature, demonstrating their quantum nature. The fluctuations appear as telegraph-like noise with a range of characteristic times and a non-monotonic temperature dependence, revealing unexpected quantum granularity. The lateral dimension of these fluctuations grows towards criticality, offering a new measurable length scale. Our results provide physical insight about the reorganization of phases across a QPT, with implications for any theoretical description. This paves a new route for future quantum information applications.

GW170817: Measurements of Neutron Star Radii and Equation of State

On 17 August 2017, the LIGO and Virgo observatories made the first direct detection of gravitational waves from the coalescence of a neutron star binary system. The detection of this gravitational-wave signal, GW170817, offers a novel opportunity to directly probe the properties of matter at the extreme conditions found in the interior of these stars. The initial, minimal-assumption analysis of the LIGO and Virgo data placed constraints on the tidal effects of the coalescing bodies, which were then translated to constraints on neutron star radii. Here, we expand upon previous analyses by working under the hypothesis that both bodies were neutron stars that are described by the same equation of state and have spins within the range observed in Galactic binary neutron stars. Our analysis employs two methods: the use of equation-of-state-insensitive relations between various macroscopic properties of the neutron stars and the use of an efficient parametrization of the defining function p(ρ) of the equation of state itself. From the LIGO and Virgo data alone and the first method, we measure the two neutron star radii as R_{1}=10.8_{-1.7}^{+2.0}  km for the heavier star and R_{2}=10.7_{-1.5}^{+2.1}  km for the lighter star at the 90% credible level. If we additionally require that the equation of state supports neutron stars with masses larger than 1.97  M_{⊙} as required from electromagnetic observations and employ the equation-of-state parametrization, we further constrain R_{1}=11.9_{-1.4}^{+1.4}  km and R_{2}=11.9_{-1.4}^{+1.4}  km at the 90% credible level. Finally, we obtain constraints on p(ρ) at supranuclear densities, with pressure at twice nuclear saturation density measured at 3.5_{-1.7}^{+2.7}×10^{34}  dyn cm^{-2} at the 90% level.

Water treatment: Mn-TiO2 synthesized by ultrasound with increased aromatics adsorption

Pharma-products are mostly single or multiple cyclic compounds. They pollute surface water and are persistent in the aquatic ecosystem. When irradiated by UV light, TiO₂ catalysts cleave or degrade organic contaminants in water. Removal of organics by photocatalysis results from a synergistic effect of adsorption and photocatalysis. Synthesis of catalysts by ultrasound (US) produces high surface area and porous solids. Here, we synthesized Mn-doped TiO₂ with a US-assisted sol-gel method. Compared to the classical synthesis, US increased the BET surface area from 83 m² g^-1 to 90 m² g^-1 in the Mn-TiO₂ sample and from 9.0 m² g^-1 to 53 m² g^-1 in the control TiO₂. Accordingly, acetaminophen and amoxicillin adsorption increased from 44% to 52%, and from 34% to 94% for the Mn-TiO₂ obtained in absence and presence of US, respectively. When in a mixture, the two drugs strongly compete for adsorption on TiO₂.

High-performance solution-based CdS-conjugated hybrid polymer solar cells

In this study, hybrid BHJ – bulk heterojunction polymer solar cells were fabricated by incorporating CdS quantum dots (QDs) in a blend of P3HT (donor) and PCBM (acceptor) using dichlorobenzene and chlorobenzene as solvents. CdS QDs at various ratios were mixed in a fixed amount of the P3HT and PCBM blend. The prepared samples have been characterized by a variety of techniques such as I–V and EQE measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM) and ultraviolet-visible (UV-vis) spectroscopy. The mixing of QDs in the polymer blends improved the PCE – power conversion efficiency of the solar cells under standard light conditions. The improved PCE from 2.95 to 4.41% is mostly due to the increase in the fill factor (FF) and short-circuit current (J_sc) of the devices with an optimum amount of CdS in the P3HT:PCBM blend. The increase in J_sc possibly originated from the formation of a percolation network of CdS. The conjugation of QDs has increased the absorption of the active layers in the visible region. These results well matched as reported, conjugation of CdS in the perovskite active layer increased the absorption and PCE of the devices relative to those of the perovskite films. This increment in parameters is attributed to the decrease in charge recombinations that improved the performance of the doped device.

In this study, hybrid BHJ – bulk heterojunction polymer solar cells were fabricated by incorporating CdS quantum dots (QDs) in a blend of P3HT (donor) and PCBM (acceptor) using dichlorobenzene and chlorobenzene as solvents.

Are Evolution and the Intracellular Innate Immune System Key Determinants in HIV Transmission?

HIV-1 is the single most important sexually transmitted disease in humans from a global health perspective. Among human lentiviruses, HIV-1 M group has uniquely achieved pandemic levels of human-to-human transmission. The requirement to transmit between hosts likely provides the strongest selective forces on a virus, as without transmission, there can be no new infections within a host population. Our perspective is that evolution of all of the virus-host interactions, which are inherited and perpetuated from host-to-host, must be consistent with transmission. For example, CXCR4 use, which often evolves late in infection, does not favor transmission and is therefore lost when a virus transmits to a new host. Thus, transmission inevitably influences all aspects of virus biology, including interactions with the innate immune system, and dictates the biological niche in which the virus exists in the host. A viable viral niche typically does not select features that disfavor transmission. The innate immune response represents a significant selective pressure during the transmission process. In fact, all viruses must antagonize and/or evade the mechanisms of the host innate and adaptive immune systems that they encounter. We believe that viewing host-virus interactions from a transmission perspective helps us understand the mechanistic details of antiviral immunity and viral escape. This is particularly true for the innate immune system, which typically acts from the very earliest stages of the host-virus interaction, and must be bypassed to achieve successful infection. With this in mind, here we review the innate sensing of HIV, the consequent downstream signaling cascades and the viral restriction that results. The centrality of these mechanisms to host defense is illustrated by the array of countermeasures that HIV deploys to escape them, despite the coding constraint of a 10 kb genome. We consider evasion strategies in detail, in particular the role of the HIV capsid and the viral accessory proteins highlighting important unanswered questions and discussing future perspectives.