Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Development of Patient-Specific Shape Memory Polymer Foams for the Treatment of Intracranial Aneurysms

The objectives of this research include: (1) designing an electrically conductive shape memory polymer (SMP) material, (2) developing a method for the systematic fabrication of SMPs with complex three-dimensional geometries based on computerized angiography tomography (CTA) of human patients, and (3) establishing translation strategies for a SMP-based endovascular device for the treatment of unruptured saccular intracranial aneurysms (ICA). We first characterized the thermomechanical properties of a porous polyurethane SMP that was infiltrated with carbon nanotubes (CNT) to induce electric conductivity in the polymeric matrix. The CNT-infiltrated SMP foams were characterized using materials science techniques that include: (i) differential scanning calorimetry (DSC) to determine the effect of CNT-infiltration on the thermal properties of the material; (ii) scanning electron microscopy (SEM) to characterize the pore morphology and interconnectivity, and (iii) uniaxial compressive testing, to characterize the effect of CNT-infiltration in the cyclic mechanical properties of the material. Then, we demonstrated the use of a CNT-infiltrated SMP foam to occlude an idealized aneurysm phantom. From these experiments, we determined that CNT-infiltrated SMP materials have the potential to be used as ICA embolic devices. However, these materials were subject to several limitations that make their translation difficult, including poor mechanical properties under cyclic compression, and a relatively high electric resistivity, that requires high currents to trigger shape recovery of the SMP. Based on the observed limitations of the CNT-infiltrated SMP material, we further performed two studies to improve the performance of our polyurethane formulation to be used as an embolic device for ICA endovascular therapy. First, we developed a method for the manufacturing of SMPs with complex 3D geometries. Due to the high degree of chemical crosslinking present in our SMP formulation, traditional 3D-printing techniques are not compatible with our material. Therefore, we developed a technique that combines leaching and 3D-printing for the fabrication of SMP foams based on CTA-informed ICA geometries. First, we fabricated polyvinyl alcohol (PVA) templates with custom pore geometries and densities. Then, we used these templates to fabricate our SMP material. By means of washing out the PVA after SMP curing, we obtained 3DSMP foams that mimicked the PVA template geometry. We also explored the effect of PVA leaching on the thermomechanical properties of the material. We found, from DSC, that the PVA leaching process induced a reduction in the glass transition temperature of the material (T_g), due to the chemical modification of the urethane groups. In addition, we found that the 3DSMP foams exhibited anisotropic mechanical properties and long-term shape recovery storage. Finally, we demonstrated the use of this manufacturing process to synthesize patient-specific 3DSMP foams. Using in vitro aneurysm models, we demonstrated that these personalized foams had the potential to provide complete ICA occlusion immediately after treatment. Building on our knowledge on the fabrication of 3DSMP foams using a leaching/3D-printing method, we aimed to induce conductivity on the 3D matrices. To do this, we performed in situ polymerization of polypyrrole (PPy), a well-described biocompatible conductive polymer, on the surface of the foams. We also modified our leaching/3D-printing method to prevent the reduction of the T_g of the material. The coating of the 3DSMP foam resulted in the induction of excellent electric conductivity on the polyurethane material. We observed that the material exhibited significantly lower resistivities than the previously developed CNT-infiltrated SMPs. This allowed the 3DSMP foams to undergo the Joule-heating process at low voltages and reach temperatures above T_g in less than 10 seconds. In addition, we developed a system to control the maximum temperature reached by the foams using pulsed electrical signals. Further, the PPy-coated 3DSMP foams underwent recovery behaviors as a response to electric stimuli. These characterizations showed the potential of the PPy-coated 3DSMP material for the development of a novel endovascular device for the treatment of unruptured saccular ICAs. In addition to the development of the material properties and functionality as an endovascular device, we also focused on planning translational research that facilitates the application of the proposed SMP-based endovascular device in the clinic. To achieve this, we first established an animal model for the testing of our embolic device in vivo prior to clinical trial studies. This animal model involves the creation of saccular aneurysms in New Zealand rabbits. Aneurysms were surgically created at the right common carotid artery by temporarily ligating the artery and then allowing an elastase solution to degrade the elastic lamina of the vascular wall. This weakening of the wall induced the bulging of the artery. In this work, we explored the stability of the aneurysms at different periods and assessed the histological structure of the aneurysms. This animal model will serve as a means to test the in vivo biocompatibility and endovascular occlusion effectiveness of our PPy-coated 3DSMP foam in the future. These future studies will be comparing the immediate and long-term occlusion effectiveness between our SMP-based device and a “gold standard” device that is currently available in the market. This comparison will demonstrate the potential superior effectiveness of our individualized treatment approach. However, selecting the gold standard as the control group is a challenging decision, due to the great diversity of modern endovascular devices for the treatment of unruptured saccular ICAs. Therefore, we performed a first-of-its-kind meta-analysis of the immediate (day 0) and long-term (post-implantation)occlusion effectiveness of modern endovascular devices. We thus performed a systematic search of studies that characterized the complete occlusion degree of ICAs of endovascular devices. Our results suggested that the most prominent endovascular devices of modern times (Guglielmi detachable coils (GDCs), flow diverters and the Woven EndoBridge) exhibit similar long-term efficacy in ICA treatment. In addition, we further showed that the immediate occlusion probability of the GDCs is the highest among the compared devices. Therefore, we selected coiling techniques as the gold standard for the in vivo assessment of endovascular embolization efficacy of our SMP-based device

Novel biopolimeric system for bone tissue engineering: Crosslinked and plasticized chitosan/poly vinyl alcohol/hydroxiapatite scaffolds

Porous scaffolds made of chitosan, polyvinyl alcohol and hydroxyapatite were prepared via freeze-drying method. In this matter, three different volume ratios of polymer solutions (1:1, 1:3, 3:1) and constant hydroxyapatite mass ratio were blended. Glutaraldehyde and glycerol were added as a polymer-chain crosslinker and plasticizer, respectively. The obtained scaffolds were used to test bone proliferation and potential for bone regeneration and they were characterized through FTIR, mechanical tests, cell cultures and swelling tests. Every quantitative measurement was statistically tested using two-way analysis of variance (ANOVA) with < 0.05. Partial results from cell culture have been obtained, showing faster cell differentiation in the scaffolds combined with glutaraldehyde and glycerol. Crosslinked scaffolds showed better swelling conditions than those that were not subject to this chemical reaction. Besides, samples with higher chitosan ratio exhibited better swelling behavior. Experiments suggest that the bio-polymeric system has potential for bone tissue regeneration. © 2018 IEEE.Universidad Manuela Beltran (Bogota, Colombia); Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504