Effect of wearing a helmet on the occurrence of head injuries in motorcycle riders in Benin: a case-control study

BACKGROUND: In Benin, motorcycles are the main means of transport for road users and are involved in more than half of crashes. This study aims to determine the effect of wearing a helmet on reducing head injuries in road crashes in Benin. METHODS: This case-control study took place in 2020 and focused on road trauma victims. The sample, consisting of 242 cases (trauma victims with head injuries) for 484 controls (without head injuries), was drawn from a database of traffic crash victims recruited from five hospitals across the country from July 2019 to January 2020. Four groups of independent variables were studied: socio-demographic and economic variables, history, behavioural variables including helmet use and road-related and environmental variables. To assess the shape of the association between the independent variables and the dependent variable, a descending step-by-step binary logistic regression model was performed using an explanatory approach. RESULTS: Fewer of the subjects with a head injury were wearing a helmet at the time of the crash 69.8% (95% CI = 63.6-75.6) compared to those without a head injury 90.3% (95% CI = 87.3-92.8). Adjusting for the other variables, subjects not wearing helmets were at greater risk of head injuries (OR = 3.8, 95% CI (2.5-5.7)); the head injury rating was 1.9 (95% CI = 1.2-3.3) times higher in subjects who were fatigued during the crash than among those who were not and 2.0 (95% CI = 1.2-3.3) times higher in subjects with no medical history. CONCLUSION: Failure to wear a helmet exposes motorcyclists to the risk of head injuries during crashes. It is important to increase awareness and better target such initiatives at the subjects most at risk

Structural effects of C60+ bombardment on various natural mineral samples—Application to analysis of organic phases in geological samples

Organic phases trapped inside natural mineral samples are of considerable interest in astrobiology, geochemistry and geobiology. Examples of such organic phases are microfossils, kerogen and oil. Information about these phases is usually retrieved through bulk crushing of the rock which means both a risk of contamination and that the composition and spatial distribution of the organics to its host mineral is lost. An attractive of way to retrieve information about the organics in the rock is depth profiling using a focused ion beam. Recently, it was shown that it is possible to obtain detailed mass spectrometric information from oil-bearing fluid inclusions, i.e. small amounts of oil trapped inside a mineral matrix, using ToF-SIMS. Using a 10 keV C-60(+) sputter beam and a 25 keV Bi-3(+) analysis beam, oil-bearing inclusions in different minerals were opened and analysed individually. However, sputtering with a C-60(+) beam also induced other changes to the mineral surface, such as formation of topographic features and carbon deposition. In this paper, the cause of these changes is explored and the consequences of the sputter-induced features on the analysis of organic phases in natural mineral samples (quartz, calcite and fluorite) in general and fluid inclusions in particular are discussed. The dominating topographical features that were observed when a several micrometers deep crater is sputtered with 10 keV C-60(+) ions on a natural mineral surface are conical-shaped and ridge-like structures that may rise several micrometers, pointing in the direction of the incident C-60(+) ion beam, on an otherwise flat crater bottom. The sputter-induced structures were found to appear at places with different chemistry than the host mineral, including other minerals phases and fluid inclusions, while structural defects in the host material, such as polishing marks or scratches, did not necessarily result in sputter-induced structures. The ridge-like structures were often covered by a thick layer of deposited carbon. Despite the appearance of the sputter-induced structures and carbon deposition, most oil-bearing inclusions could successfully be opened and analysed. However, smaller inclusion (&lt;15 mu m) could potentially become entirely covered by sputter-resistant structures and therefore difficult to open. Therefore, it might become necessary, to for example increase the ion energy and rotate the stage to successfully open smaller inclusions for analysis.</p

Analysis of hopanes and steranes in single oil-bearing fluid inclusions using time-og-flight secondary ion mass spectrometry (ToF-SIMS)

Steranes and hopanes are organic biomarkers used as indicators for the first appearance of eukaryotes and cyanobacteria on Earth. Oil-bearing fluid inclusions may provide a contamination-free source of Precambrian biomarkers, as the oil has been secluded from the environment since the formation of the inclusion. However, analysis of biomarkers in single oil-bearing fluid inclusions, which is often necessary due to the presence of different generations of inclusions, has not been possible due to the small size of most inclusions. Here, we have used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to monitor in real time the opening of individual inclusions trapped in hydrothermal veins of fluorite and calcite and containing oil from Ordovician source rocks. Opening of the inclusions was performed by using a focused C 60+ ion beam and the in situ content was precisely analysed for C27-C29 steranes and C29-C 32 hopanes using Bi3+ as primary ions. The capacity to unambiguously detect these biomarkers in the picoliter amount of crude oil from a single, normal-sized (15-30 μm in diameter) inclusion makes the approach promising in the search of organic biomarkers for life's early evolution on Earth.</p