Publications by authors named "Dylan Morris"

Objective: The health care industry accounts for 8.5% of US greenhouse gas emissions, with helicopter air ambulances (HAAs) contributing significantly. This study investigates the extent to which interfacility helicopter transfer interval affects patient outcomes, an essential consideration when optimizing flight paths.

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Background: Australia's Aboriginal and Torres Strait Islander Peoples are at high risk of peripheral arterial disease (PAD), but outcomes of revascularization are unknown. Revascularization outcomes were compared among Aboriginal and Torres Strait Islander and non-Indigenous Australians.

Methods: A retrospective cohort study was conducted of patients who underwent lower limb revascularization between January 2015 and July 2023.

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We measured stability of infectious influenza A(H5N1) virus in irradiated raw milk and wastewater and on surfaces. We found a relatively slow decay in milk, indicating that contaminated milk and fomites pose transmission risks. Although the risk is low, our results call for caution in milk handling and disposal from infected cattle.

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Objectives: Embolizing an abdominal aortic aneurysm sac through a transcaval approach is a novel approach to treat type-II endoleaks that occur following aortic endografting. This study reviews the outcomes of this treatment in one of the few centres in Australia that offers this procedure.

Methods: A retrospective cohort study was conducted, including patients who had received transcaval embolisation of type-II endoleak over a 9-year period.

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Article Synopsis
  • - Peripheral artery disease affects around 250 million people, and recent trials (BEST-CLI and BASIL-2) have aimed to determine whether bypass surgery or endovascular intervention is more effective for lower limb treatment.
  • - A systematic review of 13 studies with 3840 patients found no significant differences in major amputation or mortality rates between the two intervention methods, suggesting they are similarly effective in these outcomes.
  • - However, bypass surgery resulted in a significantly lower rate of re-intervention compared to endovascular treatment, indicating it may be a better long-term option for some patients.
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Even in large systems, the effect of noise arising from when populations are initially small can persist to be measurable on the macroscale. A deterministic approximation to a stochastic model will fail to capture this effect, but it can be accurately approximated by including an additional random time-shift to the initial conditions. We present a efficient numerical method to compute this time-shift distribution for a large class of stochastic models.

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It remains poorly understood how SARS-CoV-2 infection influences the physiological host factors important for aerosol transmission. We assessed breathing pattern, exhaled droplets, and infectious virus after infection with Alpha and Delta variants of concern (VOC) in the Syrian hamster. Both VOCs displayed a confined window of detectable airborne virus (24-48 hr), shorter than compared to oropharyngeal swabs.

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Article Synopsis
  • An outbreak of human mpox infection in nonendemic countries is largely due to transmission through body fluids or skin-to-skin contact during sexual activity.
  • Researchers evaluated how stable the monkeypox virus (MPXV) is in different environments and body fluids, finding it decayed faster at higher temperatures and varied by the medium.
  • Effective decontamination techniques included chlorination at higher concentrations, and testing wastewater for infectious MPXV could enhance surveillance efforts when a significant amount of viral DNA is present.*
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Respiratory viruses can be transmitted by multiple modes, including contaminated surfaces, commonly referred to as fomites. Efficient fomite transmission requires that a virus remain infectious on a given surface material over a wide range of environmental conditions, including different relative humidities. Prior work examining the stability of influenza viruses on surfaces has relied upon virus grown in media or eggs, which does not mimic the composition of virus-containing droplets expelled from the human respiratory tract.

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Objective: Carotid artery stenosis may present without the classical symptoms of transient ischaemic attack or stroke but the rates of stroke for these presentations is unknown. The aim of this study was to examine the rates of stroke in patients with different presentations of carotid artery stenosis.

Methods: A multicentre prospective cohort study was conducted across three Australian vascular centres with low rates of surgical treatment of patients without transient ischaemic attack or stroke.

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Objective: This retrospective cohort study investigated the anatomical distribution, severity, and outcome of peripheral artery disease (PAD) in Aboriginal and Torres Strait Islanders compared with non-indigenous Australians.

Methods: The distribution, severity, and outcome of PAD were assessed using a validated angiographic scoring system and review of medical records in a cohort of Aboriginal and Torres Strait Islander and non-indigenous Australians. The relationship between ethnicity and PAD severity, distribution, and outcome were examined using non-parametric statistical tests, Kaplan-Meier and Cox proportional hazard analyses.

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SARS-CoV-2 transmits principally by air; contact and fomite transmission may also occur. Variants of concern are more transmissible than ancestral SARS-CoV-2. We found indications of possible increased aerosol and surface stability for early variants of concern, but not for the Delta and Omicron variants.

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SARS-CoV-2 is transmitted principally via air; contact and fomite transmission may also occur. Variants-of-concern (VOCs) are more transmissible than ancestral SARS-CoV-2. We find that early VOCs show greater aerosol and surface stability than the early WA1 strain, but Delta and Omicron do not.

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Levels of sociality in nature vary widely. Some species are solitary; others live in family groups; some form complex multi-family societies. Increased levels of social interaction can allow for the spread of useful innovations and beneficial information, but can also facilitate the spread of harmful contagions, such as infectious diseases.

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Background: First Few "X" (FFX) studies provide a platform to collect the required epidemiological, clinical and virological data to help address emerging information needs about the COVID-19 pandemic.

Methods: We adapted the WHO FFX protocol for COVID-19 to understand severity and household transmission dynamics in the early stages of the pandemic in Australia. Implementation strategies were developed for participating sites; all household members were followed for 14 days from case identification.

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It remains poorly understood how SARS-CoV-2 infection influences the physiological host factors important for aerosol transmission. We assessed breathing pattern, exhaled droplets, and infectious virus after infection with Alpha and Delta variants of concern (VOC) in the Syrian hamster. Both VOCs displayed a confined window of detectable airborne virus (24-48 h), shorter than compared to oropharyngeal swabs.

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The evolution of complex cellular life involved two major transitions: the encapsulation of self-replicating genetic entities into cellular units and the aggregation of individual genes into a collectively replicating genome. In this paper, we formulate a minimal model of the evolution of proto-chromosomes within protocells. We model a simple protocell composed of two types of genes: a "fast gene" with an advantage for gene-level self-replication and a "slow gene" that replicates more slowly at the gene level, but which confers an advantage for protocell-level reproduction.

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Noninvasive ventilation (NIV), including bilevel positive airway pressure and continuous positive airway pressure, is a safe and important therapeutic option in the management of prehospital respiratory distress. NAEMSP recommends:NIV should be used in the management of prehospital patients with respiratory failure, such as those with chronic obstructive pulmonary disease, asthma, and pulmonary edema.NIV is a safe intervention for use by Emergency Medical Technicians.

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Article Synopsis
  • The Metformin Aneurysm Trial (MAT) aims to determine if metformin can lower the risk of complications like rupture or surgery in patients with asymptomatic abdominal aortic aneurysms (AAA).
  • The study is a double-blind, placebo-controlled trial involving participants with a AAA of at least 35mm, assessing outcomes such as AAA events, growth, and quality of life, requiring a substantial number of participants for robust results.
  • MAT is particularly significant as it specifically investigates metformin's effects on AAA outcomes, in contrast to previous trials focused on other medications, amidst challenges posed by the ongoing COVID-19 pandemic.
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Objective: Observational studies demonstrate an inverse association between type II diabetes and abdominal aortic aneurysm (AAA) for reasons that are unclear. The aim of this study was to clarify the causal association between type II diabetes predisposition and AAA using Mendelian randomisation.

Methods: Effect estimates for single nucleotide polymorphisms (SNPs) associated with diabetes were obtained from the DIAbetes Meta-ANalysis of Trans-Ethnic association studies (DIAMANTE) consortium to construct a genetic instrumental variable.

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Decontamination helps limit environmental transmission of infectious agents. It is required for the safe reuse of contaminated medical, laboratory, and personal protective equipment, and for the safe handling of biological samples. Heat treatment is a common decontamination method, notably used for viruses.

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Introduction: Mendelian randomisation (MR) has been suggested to be able to overcome biases of observational studies, but no meta-analysis is available on MR studies on abdominal aortic aneurysm (AAA). This systematic review and Meta-analysis examined the evidence of causal risk factors for AAA identified in MR studies.

Methods: Publicly available databases were systematically searched for MR studies that reported any causal risk factors for AAA diagnosis.

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Ambient temperature and humidity strongly affect inactivation rates of enveloped viruses, but a mechanistic, quantitative theory of these effects has been elusive. We measure the stability of SARS-CoV-2 on an inert surface at nine temperature and humidity conditions and develop a mechanistic model to explain and predict how temperature and humidity alter virus inactivation. We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities (RH); median estimated virus half-life is >24 hr at 10°C and 40% RH, but ∼1.

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