In this paper we develop a simple model of the inhaled flow rate of aerosol particles of respiratory origin i.e. that have been exhaled by other people. A connection is made between the exposure dose ...and the probability of developing an airborne disease. This allows a simple assessment of the outdoor versus indoor risk of contamination to be made in a variety of meteorological situations. It is shown quantitatively that for most cases, the outdoor risk is orders of magnitude less than the indoor risk and that it can become comparable only for extremely specific meteorological and topographical situations. It sheds light on various observations of COVID-19 spreading in mountain valleys with temperature inversions while at the same time other areas are much less impacted.
•Risk of COVID-19 airborne transmission.•Quantitative assessment of outdoor versus indoor airborne risk of transmission.•Meteorological and topographical influence on COVID-19 airborne transmission.
ABSTRACT In recent years, ultra-low temperature chemical kinetic experiments have demonstrated that some gas-phase reactions are much faster than was previously thought. One example is the reaction ...between OH and CH3OH, which has recently been found to be accelerated at low temperatures yielding CH3O as its main product. This finding raised the question of whether or not the CH3O observed in the dense core Barnard 1b could be formed by the gas-phase reaction of CH3OH and OH. Several chemical models including this reaction and grain-surface processes have been developed to explain the observed abundance of CH3O, but they have met with little success. Here, we report for the first time the rate coefficients for the gas-phase reaction of OH and CH3OH down to a temperature of 22 K, which is very close to the temperature in cold interstellar clouds. Two independent experimental set-ups based on the supersonic gas expansion technique coupled to the pulsed laser photolysis laser-induced fluorescence technique were used to determine the rate coefficients in the temperature range 22-64 K. The temperature dependence obtained in this work can be expressed as k(22-64 K) = ( 3.6 0.1 ) × 10 − 12 ( T / 300 K ) − ( 1.0 0.2 ) cm3 molecule−1 s−1. Implementing this expression in a chemical model of a cold, dense cloud results in CH3O/CH3OH abundance ratios similar to or slightly lower than the value of ∼3 × 10−3 observed in Barnard 1b. This finding confirms that the gas-phase reaction between OH and CH3OH is an important contributor to the formation of interstellar CH3O. The role of grain-surface processes in the formation of CH3O, although it cannot be fully neglected, remains controversial.
There is less data available regarding the characteristics of cognitive impairment in patients with amyotrophic lateral sclerosis (ALS) in a population-based series.
Patients with ALS incident in ...Piemonte, Italy, between 2009 and 2011 underwent an extensive neuropsychological battery. Cognitive status was classified as follows: normal cognition, frontotemporal dementia (ALS-FTD), executive cognitive impairment (ALS-ECI), non-executive cognitive impairment (ALS-NECI), behavioural impairment (ALS-Bi), non-classifiable cognitive impairment. We also assessed 127 age-matched and gender-matched controls identified through patients' general practitioners.
Out of the 281 incident patients, 207 (71.9%) underwent the neuropsychological testing; of these, 19 were excluded from the analysis due previous conditions affecting cognition. Ninety-one (49.7%) patients were cognitively normal, 23 (12.6%) had ALS-FTD, 36 (19.7%) ALS-ECI, 10 (5.5%) ALS-NECI, 11 (6.0%) ALS-Bi and 11 (6.0%) non-classifiable cognitive impairment, 1 had comorbid Alzheimer's disease. Patients with ALS-FTD were older, had a lower education level, and had a shorter survival than any other cognitive group. Of the nine cases with C9ORF72 mutation, six had ALS-FTD, two ALS-ECI and one was cognitively normal; one of the five patients with SOD1 mutations and one of the five patients with TARBDP mutations had ALS-Bi.
About 50% of Italian patients with ALS had some degree of cognitive impairment, in keeping with a previous Irish study, despite the largely different genetic background of the two populations. The lower educational attainment in patients with ALS-FTD indicated a possible role of cognitive reserve in ALS-related cognitive impairment. ALS-ECI and ALS-NECI may represent discrete cognitive syndromes in the continuum of ALS and FTD.
The chemical kinetics of neutral-neutral gas-phase reactions at ultralow temperatures is a fascinating research subject with important implications on the chemistry of complex organic molecules in ...the interstellar medium (T ∼ 10-100 K). Scarce kinetic information is currently available for these kinds of reactions at T < 200 K. In this work, we use the Cinétique de Réaction en Ecoulement Supersonique Uniforme (CRESU; Reaction Kinetics in a Uniform Supersonic Flow) technique to measure for the first time the rate coefficients (k) of the gas-phase OH+H2CO reaction between 22 and 107 K. The k values greatly increase from 2.1 × 10−11 cm3 s−1 at 107 K to 1.2 × 10−10 cm3 s−1 at 22 K. This is also confirmed by quasi-classical trajectories (QCT) at collision energies down to 0.1 meV performed using a new full dimension and ab initio potential energy surface that generates highly accurate potential and includes long-range dipole-dipole interactions. QCT calculations indicate that at low temperatures HCO is the exclusive product for the OH+H2CO reaction. In order to revisit the chemistry of HCO in cold dense clouds, k is reasonably extrapolated from the experimental results at 10 K (2.6 × 10−10 cm3 s−1). The modeled abundances of HCO are in agreement with the observations in cold dark clouds for an evolving time of 105-106 yr. The different sources of production of HCO are presented and the uncertainties in the chemical networks are discussed. The present reaction is shown to account for a few percent of the total HCO production rate. This reaction can be expected to be a competitive process in the chemistry of prestellar cores. Extensions to photodissociation regions and diffuse cloud environments are also addressed.
Background and purpose: To assess the prevalence and characteristics of pain in an epidemiological series of patients with amyotrophic lateral sclerosis (ALS) compared to population‐based controls.
...Methods: Of the 183 patients with ALS resident in the province of Torino, Italy, 160 accepted to be interviewed. Controls were randomly selected from the lists of general practitioners. Pain was assessed using the Brief Pain Inventory.
Results: Patients with ALS reported pain more frequently than controls 91 (56.9%) vs. 53 (33.1%); P = 0.001. Pain frequency and intensity were correlated with a worse functional score and a longer disease duration. In patients with ALS, pain was more frequently located at the extremities (P = 0.006). Pain interfered with all areas of daily function, but patients reported a greater interference than controls in the domains of enjoyment of life and relation with other people. Sixty‐four patients (70.3% of those with pain) and 24 controls (45.3% of those with pain) (P = 0.003) were treated for pain, most frequently with non‐steroidal anti‐inflammatory drugs. ALS cases were also more frequently prescribed non‐opioid analgesics and opioids than controls.
Conclusions: Our study indicates that pain is frequent in all stages of ALS, but that it often goes underrecognized and undertreated. It is significantly more frequent in patients with ALS than in population‐based controls. Future studies need to clarify the mechanisms of pain in ALS and determine the most effective treatment strategy.
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To assess the effect of eligibility criteria in amyotrophic lateral sclerosis (ALS) clinical trials on the representativeness of the enrolled population.
Patients enrolled in 8 placebo-controlled ...clinical trials in our ALS center from 2003 to 2008 were compared 1) to the patients included a prospective epidemiologic register (Piemonte and Valle d'Aosta register for ALS, PARALS) in the same period and 2) the subset of PARALS patients who met the usual criteria for inclusion in clinical trials (PARALS-ct) (definite, probable, probable laboratory-supported ALS; age between 18 and 75 years; disease duration <36 months; vital capacity at diagnosis ≥70%; score ≥3 at the items swallowing and respiratory insufficiency at the Amyotrophic Lateral Sclerosis Functional Rating Scale-revised scale; riluzole therapy).
A total of 164 patients were enrolled in 8 different clinical trials. The PARALS cohort included 813 patients, of whom 539 (66.3%) met the entry criteria for clinical trials. Patients enrolled in clinical trials were different from both epidemiologic cohorts, since they were younger, had a longer diagnostic delay, and were more likely to have a spinal onset, and to be men. Tracheostomy-free survival was significantly longer in the group of patients enrolled in clinical trials (median survival time, trial patients, 3.9 years 95% confidence interval (CI) 3.4-4.4; PARALS, 2.6 2.4-2.8; PARALS-ct, 2.9 2.7-3.1).
Patients enrolled in clinical trials do not satisfactorily represent the ALS population; consequently, the findings of ALS trials lack of external validity (generalizability). Efforts should be made to improve patients' recruitment in trials, particularly enrolling incident rather than prevalent cases.
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