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result(s) for
"Gatey, David"
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Evaluation of Urban Local-Scale Aerodynamic Parameters: Implications for the Vertical Profile of Wind Speed and for Source Areas
by
Grimmond, Sue
,
Barlow, Janet
,
Kent, Christoph W.
in
Aerodynamic roughness length
,
Aerodynamics
,
Anemometric methods
2017
Nine methods to determine local-scale aerodynamic roughness length
(
z
0
)
and zero-plane displacement
(
z
d
)
are compared at three sites (within 60 m of each other) in London, UK. Methods include three anemometric (single-level high frequency observations), six morphometric (surface geometry) and one reference-based approach (look-up tables). A footprint model is used with the morphometric methods in an iterative procedure. The results are insensitive to the initial
z
d
and
z
0
estimates. Across the three sites,
z
d
varies between 5 and 45 m depending upon the method used. Morphometric methods that incorporate roughness-element height variability agree better with anemometric methods, indicating
z
d
is consistently greater than the local mean building height. Depending upon method and wind direction,
z
0
varies between 0.1 and 5 m with morphometric
z
0
consistently being 2–3 m larger than the anemometric
z
0
. No morphometric method consistently resembles the anemometric methods. Wind-speed profiles observed with Doppler lidar provide additional data with which to assess the methods. Locally determined roughness parameters are used to extrapolate wind-speed profiles to a height roughly 200 m above the canopy. Wind-speed profiles extrapolated based on morphometric methods that account for roughness-element height variability are most similar to observations. The extent of the modelled source area for measurements varies by up to a factor of three, depending upon the morphometric method used to determine
z
d
and
z
0
.
Journal Article
Aerodynamic roughness variation with vegetation: analysis in a suburban neighbourhood and a city park
2018
Local aerodynamic roughness parameters (zero-plane displacement, zd, and aerodynamic roughness length, z0) are determined for an urban park and a suburban neighbourhood with a new morphometric parameterisation that includes vegetation. Inter-seasonal analysis at the urban park demonstrates zd determined with two anemometric methods is responsive to vegetation state and is 1–4 m greater during leaf-on periods. The seasonal change and directional variability in the magnitude of zd is reproduced by the morphometric methods, which also indicate z0 can be more than halved during leaf-on periods. In the suburban neighbourhood during leaf-on, the anemometric and morphometric methods have similar directional variability for both zd and z0. Wind speeds at approximately 3 times the average roughness-element height are estimated most accurately when using a morphometric method which considers roughness-element height variability. Inclusion of vegetation in the morphometric parameterisation improves wind-speed estimation in all cases. Results indicate that the influence of both vegetation and roughness-element height variability are important for accurate determination of local aerodynamic parameters and the associated wind-speed estimates.
Journal Article
Erratum to: Evaluation of Urban Local-Scale Aerodynamic Parameters: Implications for the Vertical Profile of Wind Speed and for Source Areas
by
Grimmond, Sue
,
Barlow, Janet
,
Kent, Christoph W.
in
Atmospheric Protection/Air Quality Control/Air Pollution
,
Atmospheric Sciences
,
Earth and Environmental Science
2017
Journal Article
The Analysis of Extreme Synoptic Winds
Time histories of wind speed and direction from 394 surface observation stations were obtained to calculate synoptic 50-year return period wind speeds for 11 countries in Europe. Preliminary investigation indicated wind speed differences along national borders were successfully reduced by application of a simple consistent methodology to wind speed data. This study considers the ideal methodology for calculating synoptic 50-year return period wind speeds. Wind speed data requires standardisation through quality control measures, exposure correction and adjustment for disjunct sampling. A quality control algorithm was successfully applied to identify shifts of monthly mean wind speeds and data conversion issues. Three exposure correction models were evaluated and two-layer models were found to perform better than internal boundary layer models. The differences arise as a result of how the models adapt to an upstream change of roughness. Furthermore, an empirical model was formed to correct observations at stations which were not recording measurements hourly. Extreme value analyses were carried out using a robust estimator to fit the extreme value distribution type I to storm and yearly maxima. The latter was found to provide more consistent results. Comparison of the resulting 50-year return period wind speeds to existing literature found that several regions were in good agreement, while other regions exhibited similar spatial variation but greater magnitudes. The differences in magnitude were partially related to exposure correction methods, thus lending support to the importance of a single consistent methodology. Directional factors were calculated and subsequently grouped into six regions exhibiting similar directional characteristics. Background wind fields were calculated from mean sea-level pressure data using the geostrophic approximation and consideration of other improved approximations, however, variations in the pressure field led to a breakdown of the methodology. A background 50-year return period wind field calculated from upper-level wind fields was significantly lower than surface wind speed estimates due to spatial and temporal smoothing. Finally, assimilation of the 50-year return period wind speeds from surface observations and the background wind field was explored using the Bratseth scheme for statistical interpolation. The Bratseth scheme provided an overall 50-year return period wind speed map.
Dissertation
Mycoplasma pneumoniae infection in adult inpatients during the 2023–24 outbreak in France (MYCADO): a national, retrospective, observational study
2025
An epidemic of Mycoplasma pneumoniae infection has been observed in France since September, 2023. We aimed to describe the characteristics of adults hospitalised for M pneumoniae infection and identify factors associated with severe outcomes of infection.
MYCADO is a retrospective observational study including adults hospitalised for 24 h or more in 76 hospitals in France for a M pneumoniae infection between Sept 1, 2023, and Feb 29, 2024. Clinical, laboratory, and imaging data were collected from medical records. We identified factors associated with severe outcomes of infection, defined as a composite of intensive care unit (ICU) admission or in-hospital death, using multivariable logistic regression.
1309 patients with M pneumoniae infection were included: 718 (54·9%) were men and 591 (45·1%) were women; median age was 43 years (IQR 31–63); 288 (22·0%) had chronic respiratory failure; 423 (32·3%) had cardiovascular comorbidities; and 105 (8·0%) had immunosuppression. The most common symptoms were cough (1098 [83·9%]), fever (1023 [78·2%]), dyspnoea (948 [72·4%]), fatigue (550 [42·0%]), expectorations (473 [36·1%]), headache (211 [16·1%]), arthromyalgia (253 [19·3%]), ear, nose, and throat symptoms (202 [15·4%]), diarrhoea (138 [10·5%]), and vomiting (132 [10·1%]). 156 (11·9%) of 1309 patients had extra-respiratory manifestations, including 36 (2·8%) with erythema multiforme, 19 (1·5%) with meningoencephalitis, 44 (3·4%) with autoimmune haemolytic anaemia, and 17 (1·3%) with myocarditis. The median hospital stay was 8 days (IQR 6–11). 424 (32·4%) patients had a severe outcome of infection, including 415 (31·7%) who were admitted to the ICU and 28 (2·1%) who died in hospital. Those more likely to present with severe outcomes of infection were patients with hypertension, obesity, chronic liver failure, extra-respiratory manifestations, pulmonary alveolar consolidation or bilateral involvement on CT scan, as well as elevated inflammatory markers, lymphopenia or neutrophilic polynucleosis, and those who did not versus did receive any antibiotic active against M pneumoniae before admission.
This national, observational study highlighted unexpected, atypical radiological presentations, a high proportion of transfers to the ICU, and an association between severity and delayed administration of effective antibiotics. This should remind clinicians that no radiological presentation can rule out M pneumoniae infection, and encourage them to reassess patients early after prescribing a β-lactam, or even to discuss prescribing macrolides as first-line treatment in the context of an epidemic.
None.
For the French translation of the abstract see Supplementary Materials section.
Journal Article
Effect of On-Demand Oral Pre-exposure Prophylaxis With Tenofovir/Emtricitabine on Herpes Simplex Virus-1/2 Incidence Among Men Who Have Sex With Men: A Substudy of the ANRS IPERGAY Trial
2018
We evaluated the impact of on-demand oral tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) for pre-exposure prophylaxis (PrEP) on herpes simplex virus (HSV)-1/2 incidence among men who have sex with men (MSM) enrolled in the ANRS IPERGAY trial. Serum samples were tested at baseline and at the last visit for HSV-1/2 antibodies. Overall HSV-1 incidence was 11.7 per 100 person-years; 16.2 and 7.8 per 100 person-years in the TDF/FTC and placebo arm, respectively (P = .19). Overall HSV-2 incidence was 7.6 per 100 person-years; 8.1 and 7.0 per 100 person-years in the TDF/FTC and placebo arm, respectively (P = .75). On-demand oral PrEP with TDF/FTC failed to reduce HSV-1/2 incidence in this population.
Journal Article