Search

The PICASSO and COUPP collaborations use superheated liquid detectors to search for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs). These experiments, located in the underground laboratory of SNOLAB, Canada, detect phase transitions triggered by nuclear recoils in the keV range induced by interactions with WIMPs. We present details of the construction and operation of these detectors as well as the results, obtained by several years of observations. We also introduce PICO, a joint effort of the two collaborations to build a second generation ton-scale bubble chamber with 250 liters of active liquid.

Abstract: Recent results from the PICASSO dark matter search experiment at SNOLAB are reported. These results were obtained using a subset of 10 detectors with a total target mass of 0.72 kg of 19F and an exposure of 114 kgd. The low backgrounds in PICASSO allow recoil energy thresholds as low as 1.7 keV to be obtained which results in an increased sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs) with masses below 10 GeV/c2. No dark matter signal was found. Best exclusion limits in the spin dependent sector were obtained for WIMP masses of 20 GeV/c2 with a cross section on protons of (90% C.L.). In the spin independent sector close to the low mass region of 7 GeV/c2 favoured by CoGeNT and DAMA/LIBRA, cross sections larger than (90% C.L.) are excluded. [Copyright &y& Elsevier]

Objective: To compare health outcomes and costs given in the emergency department (ED) and walk-in clinics for ambulatory children presenting with acute respiratory diseases., Design: A retrospective cohort study., Setting: This study was conducted from April 2016 to March 2017 in one ED and one walk-in clinic. The ED is a paediatric tertiary care centre, and the clinic has access to lab tests and X-rays., Participants: Inclusion criteria were children: (1) aged from 2 to 17 years old and (2) discharged home with a diagnosis of upper respiratory tract infection (URTI), pneumonia or acute asthma., Main Outcome Measures: The primary outcome measure was the proportion of patients returning to any ED or clinic within 3 and 7 days of the index visit. The secondary outcome measures were the mean cost of care estimated using time-driven activity-based costing and the incidence of antibiotic prescription for URTI patients., Results: We included 532 children seen in the ED and 201 seen in the walk-in clinic. The incidence of return visits at 3 and 7 days was 20.7% and 27.3% in the ED vs 6.5% and 11.4% in the clinic (adjusted relative risk at 3 days (aRR) (95% CI) 3.17 (1.77 to 5.66) and aRR at 7 days 2.24 (1.46 to 3.44)). The mean cost (95% CI) of care (CAD) at the index visit was $C96.68 (92.62 to 100.74) in the ED vs $C48.82 (45.47 to 52.16) in the clinic (mean difference (95% CI): 46.15 (41.29 to 51.02)). Antibiotic prescription for URTI was less common in the ED than in the clinic (1.5% vs 16.4%; aRR 0.10 (95% CI 0.03 to 0.32))., Conclusions: The incidence of return visits and cost of care were significantly higher in the ED, while antibiotic use for URTI was more frequent in the walk-in clinic. These data may help determine which setting offers the highest value to ambulatory children with acute respiratory conditions., Competing Interests: Competing interests: SBerthelot, LM, DT, PA and JRG currently hold FRQS research scholarships., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: The CyberKnife system is a robotic radiosurgery platform that allows the delivery of lung SBRT treatments using fiducial-free soft-tissue tracking. However, not all lung cancer patients are eligible for lung tumor tracking. Tumor size, density, and location impact the ability to successfully detect and track a lung lesion in 2D orthogonal X-ray images. The standard workflow to identify successful candidates for lung tumor tracking is called Lung Optimized Treatment (LOT) simulation, and involves multiple steps from CT acquisition to the execution of the simulation plan on CyberKnife. The aim of the study is to develop a deep learning classification model to predict which patients can be successfully treated with lung tumor tracking, thus circumventing the LOT simulation process., Methods: Target tracking is achieved by matching orthogonal X-ray images with a library of digital radiographs reconstructed from the simulation CT scan (DRRs). We developed a deep learning model to create a binary classification of lung lesions as being trackable or untrackable based on tumor template DRR extracted from the CyberKnife system, and tested five different network architectures. The study included a total of 271 images (230 trackable, 41 untrackable) from 129 patients with one or multiple lung lesions. Eighty percent of the images were used for training, 10% for validation, and the remaining 10% for testing., Results: For all five convolutional neural networks, the binary classification accuracy reached 100% after training, both in the validation and the test set, without any false classifications., Conclusions: A deep learning model can distinguish features of trackable and untrackable lesions in DRR images, and can predict successful candidates for fiducial-free lung tumor tracking., (© 2023 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.)

Objectives: Our aim was to compare some of the health outcomes and costs associated with value of care in emergency departments (ED) and walk-in clinics for ambulatory patients presenting with an acute respiratory disease., Methods: A health records review was conducted from April 2016 through March 2017 in one ED and one walk-in clinic. Inclusion criteria were: (i) ambulatory patients at least 18 years old, (ii) discharged home with a diagnosis of upper respiratory tract infection (URTI), pneumonia, acute asthma, or acute exacerbation of chronic obstructive pulmonary disease. Primary outcome was the proportion of patients returning to any ED or walk-in clinic within three and seven days of the index visit. Secondary outcomes were the mean cost of care and the incidence of antibiotic prescription for URTI patients. The cost of care was estimated from the Ministry of Health's perspectives using time-driven activity-based costing., Results: The ED group included 170 patients and the walk-in clinic group 326 patients. The return visit incidences at three and seven days were, respectively, 25.9% and 38.2% in the ED vs. 4.9% and 14.7% in the walk-in clinic (adjusted relative risk (arr) of 4.7 (95% CI 2.6-8.6) and 2.7 (1.9-3.9)). The mean cost ($Cdn) of the index visit care was 116.0 (106.3-125.7) in the ED vs. 62.5 (57.7-67.3) in the walk-in clinic (mean difference of 56.4 (45.7-67.1)). Antibiotic prescription for URTI was 5.6% in the ED vs. 24.7% in the walk-in clinic (arr 0.2, 0.01-0.6)., Conclusions: This study is the first in a larger research program to compare the value of care between walk-in clinics and the ED. The potential advantages of walk-in clinics over EDs (lower costs, lower incidence of return visits) for ambulatory patients with respiratory diseases should be considered in healthcare planning., (© 2023. The Author(s), under exclusive licence to Canadian Association of Emergency Physicians (CAEP)/ Association Canadienne de Médecine d'Urgence (ACMU).)

Multi-drug-resistant bacteria present an urgent threat to modern medicine, creating a desperate need for antibiotics with new modes of action. As natural products remain an unsurpassed source for clinically viable antibiotic compounds, we investigate the mechanism of action of armeniaspirol. The armeniaspirols are a structurally unique class of Gram-positive antibiotic discovered from Streptomyces armeniacus for which resistance cannot be readily obtained. We show that armeniaspirol inhibits the ATP-dependent proteases ClpXP and ClpYQ in vitro and in the model Gram-positive Bacillus subtilis. This inhibition dysregulates the divisome and elongasome supported by an upregulation of key proteins FtsZ, DivIVA, and MreB inducing cell division arrest. The inhibition of ClpXP and ClpYQ to dysregulate cell division represents a unique antibiotic mechanism of action and armeniaspirol is the only known natural product inhibitor of the coveted anti-virulence target ClpP. Thus, armeniaspirol possesses a promising lead scaffold for antibiotic development with unique pharmacology., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Organochlorine pesticides and polychlorinated biphenyls (PCBs) are ubiquitous and persistent in the environment. They are known to concentrate in cold environments as a result of progressive evaporation from warm regions, and condensation in colder regions. In this study we show that melting glaciers supply 50 to 97% of the organochlorine inputs to a subalpine lake in Alberta, Canada, while contributing 73% of input water. Tritium analyses indicated that during the mid- to late summer warm period, at least 10% of the glacial melt originated from ice that was deposited in 1950-1970, when it was more contaminated with organochlorines. This finding suggests that climate warming may cause melting glaciers to become increasing sources of contaminants to freshwaters. Organochlorines from glacial streams were largely in dissolved form because the organic-poor glacial clays had a limited sorption capacity for the more hydrophobic chemicals.

This article discusses research on the difficulties of practising social work in a multicultural and multiethnic context. The research is based on critical incidents that were experienced by 40 social workers in "the most ethnic" public social service centres of the Montréal region in 1990-1992. The most significant culture shocks that occurred between workers of a developed Western-type society and clients from developing, non-Western societies relate to a different notion of the role of social services, to different methods et educating children, to unequal relationship between men and women, to a different notion of family and to a different notion of physical and mental health. The authors emphasize that a better understanding of these shocks and an effort to identify and analyze these sensitive zones of intercultural encounter can have a definite impact on the practice and training of social workers.