La médecine légale : une discipline médiatique et médiatisée

Pendant longtemps, la médecine légale est restée une discipline mal ou peu connue, en marge de la médecine conventionnelle. Actuellement, le domaine est mieux perçu par le public, notamment grâce à l'image qu'en reflètent les médias. Il n'empêche que le médecin légiste reste, à l'aune du 3e millénaire, un personnage énigmatique dont la profession attire, voire fascine, mais dont la formation et le rôle demeurent encore mal définis: est-il un vrai médecin? Un juriste? Est-il les deux à la fois? Au fil des ans, la formation de médecin légiste s'est complexifiée et son rôle s'est accru, du fait des progrès de la médecine et de la police scientifique, ainsi que de l'émergence de nouveaux besoins et domaines d'investigation

Characterization of the Intra-Unit-Cell magnetic order in Bi2Sr2CaCu2O8+d

As in YBa2Cu3O6+x and HgBa2CuO8+d, the pseudo-gap state in Bi2Sr2CaCu2O8+d is characterized by the existence of an intra-unit-cell magnetic order revealed by polarized neutron scattering technique. We report here a supplementary set of polarized neutron scattering measurements for which the direction of the magnetic moment is determined and the magnetic intensity is calibrated in absolute units. The new data allow a close comparison between bilayer systems YBa2Cu3O6+x and Bi2Sr2CaCu2O8+d and rise important questions concerning the range of the magnetic correlations and the role of disorder around optimal doping.Comment: 12 pages, 8 figures, submitted to physical review

Instruments for investigating fitness to drive - needs and expectations in primary care: a qualitative study

Background: Primary care physicians are often requested to assess their patients' fitness to drive. Little is however known on their needs to help them in this task. Aims: The aim of this study is to develop theories on needs, expectations, and barriers for clinical instruments helping physicians assess fitness to drive in primary care. Methods: This qualitative study used semi-structured interviews to investigate needs and expectations for instruments used to assess fitness to drive. From August 2011 to April 2013, we recorded opinions from five experts in traffic medicine, five primary care physicians, and five senior drivers. All interviews were integrally transcribed. Two independent researchers extracted, coded, and stratified categories relying on multi-grounded theory. All participants validated the final scheme. Results: Our theory suggests that for an instruments assessing fitness to drive to be implemented in primary care, it need to contribute to the decisional process. This requires at least five conditions: 1) it needs to reduce the range of uncertainty, 2) it needs to be adapted to local resources and possibilities, 3) it needs to be accepted by patients, 4) choices of tasks need to adaptable to clinical conditions, 5) and interpretation of results need to remain dependant of each patient's context. Discussion and conclusions: Most existing instruments assessing fitness to drive are not designed for primary care settings. Future instruments should also aim to support patient-centred dialogue, help anticipate driving cessation, and offer patients the opportunity to freely take their own decision on driving cessation as often as possible

Bayesian detection of abnormal hematological values to introduce a no-start rule for heterogeneous populations of athletes.

Sports authorities exclude athletes with abnormal levels of blood parameters. Here, the consideration of longitudinal blood profiles together with heterogeneous factors such as ethnicity and age produces a model with enhanced sensitivity to detect blood doping. Sports disciplines with heterogeneous populations now have a general method to introduce the no-start rule

New reference tables and user-friendly Internet application for predicted heart weights.

Knowledge of normal heart weight ranges is important information for pathologists. Comparing the measured heart weight to reference values is one of the key elements used to determine if the heart is pathological, as heart weight increases in many cardiac pathologies. The current reference tables are old and in need of an update. The purposes of this study are to establish new reference tables for normal heart weights in the local population and to determine the best predictive factor for normal heart weight. We also aim to provide technical support to calculate the predictive normal heart weight. The reference values are based on retrospective analysis of adult Caucasian autopsy cases without any obvious pathology that were collected at the University Centre of Legal Medicine in Lausanne from 2007 to 2011. We selected 288 cases. The mean age was 39.2 years. There were 118 men and 170 women. Regression analyses were performed to assess the relationship of heart weight to body weight, body height, body mass index (BMI) and body surface area (BSA). The heart weight increased along with an increase in all the parameters studied. The mean heart weight was greater in men than in women at a similar body weight. BSA was determined to be the best predictor for normal heart weight. New reference tables for predicted heart weights are presented as a web application http://calc.chuv.ch/Heartweight#use that enable the comparison of heart weights observed at autopsy with the reference values. The reference tables for heart weight and other organs should be systematically updated and adapted for the local population. Web access and smartphone applications for the predicted heart weight represent important investigational tools

Diagnostic performance of urinary metanephrines for the postmortem diagnosis of hypothermia.

The purpose of this study was to assess the diagnostic potential of urinary metanephrines and 3-methoxytyramine compared to urinary catecholamine determination in diagnosing antemortem cold exposure and fatal hypothermia. 83 cases of fatal hypothermia and 144 control cases were included in this study. Catecholamines (adrenaline, noradrenaline and dopamine), metanephrines (metanephrine, normetanephrine) and 3-methoxytyramine were measured in urine collected during autopsy. All tested analytes were significantly higher in hypothermia cases compared to control subjects and displayed a generally satisfying discriminative value, thus indicating urinary catecholamines and their metabolites as reliable markers of cold-related stress and hypothermia related-deaths. Metanephrine and adrenaline had the best discriminative value between hypothermia and control cases compared to other tested analytes, though with different sensitivity and specificity. These can therefore be considered the most suitable markers of cold-related stress

The trail making test as a screening instrument for driving performance in older drivers; a translational research.

BACKGROUND: In many countries, primary care physicians determine whether or not older drivers are fit to drive. Little, however, is known regarding the effects of cognitive decline on driving performance and the means to detect it. This study explores to what extent the trail making test (TMT) can provide indications to clinicians about their older patients' on-road driving performance in the context of cognitive decline. METHODS: This translational study was nested within a cohort study and an exploratory psychophysics study. The target population of interest was constituted of older drivers in the absence of important cognitive or physical disorders. We therefore recruited and tested 404 home-dwelling drivers, aged 70 years or more and in possession of valid drivers' licenses, who volunteered to participate in a driving refresher course. Forty-five drivers also agreed to undergo further testing at our lab. On-road driving performance was evaluated by instructors during a 45 minute validated open-road circuit. Drivers were classified as either being excellent, good, moderate, or poor depending on their score on a standardized evaluation of on-road driving performance. RESULTS: The area under the receiver operator curve for detecting poorly performing drivers was 0.668 (CI95% 0.558 to 0.778) for the TMT-A, and 0.662 (CI95% 0.542 to 0.783) for the TMT-B. TMT was related to contrast sensitivity, motion direction, orientation discrimination, working memory, verbal fluency, and literacy. Older patients with a TMT-A ≥ 54 seconds or a TMT-B ≥ 150 seconds have a threefold (CI95% 1.3 to 7.0) increased risk of performing poorly during the on-road evaluation. TMT had a sensitivity of 63.6%, a specificity of 64.9%, a positive predictive value of 9.5%, and a negative predictive value of 96.9%. CONCLUSION: In screening settings, the TMT would have clinicians uselessly consider driving cessation in nine drivers out of ten. Given the important negative impact this could have on older drivers, this study confirms the TMT not to be specific enough for clinicians to justify driving cessation without complementary investigations on driving behaviors

Cyclonickellation des phosphinites dérivées de phénols et naphtols : r égiosélectivité, mécanisme, fonctionnalisation et formation de nouveaux pinceurs

Cette thèse présente différents aspects de la cyclonickellation des phosphinites de type Aryl-OP(i-Pr)2, leur potentiel dans la fonctionnalisation et leur utilité pour former des nouveaux types de complexes de types pincer de nickel. Le Chapitre 1 constitue une introduction générale sur l’importance de la liaison carbone-nickel en chimie organométallique. Diverses stratégies de formation des liens C-Ni dans des composés classiques (monodentés), des composés de types pincer (tridentés) et des composé cyclonickellés (bidentés et tridentés) y sont présentées, incluant des réactions impliquant des précurseurs de Ni0, de NiII ou de NiIV. Ce chapitre présente également la réactivité de ces composés comportant des liens C-Ni, et met l’emphase sur la réactivité des liaisons carbone-nickel, en particulier dans les processus catalytiques destinés à la fonctionnalisation des liens C-H, en utilisant des groupes directeurs. Les phosphinites sont ensuite présentées comme des groupes directeurs intéressants en catalyse, bien qu’elles aient surtout été utilisé avec d’autres métaux que le nickel. La dernière partie de ce chapitre pose les questions qui tenterons de trouver réponse dans les travaux présentés aux chapitres suivants. Les Chapitres 2 et 4, basés sur des articles publiés, présentent l’isolation et la caractérisation de composés dimériques de type [{κP,κC-(i-Pr)2POAr}Ni(μ-Br)]2 issus de l’ortho-nickellation des phosphinites dérivées des phénols et des naphtols substitués, ainsi que de certains de leurs adduits monomériques d’acétonitrile ou du ligand lui-même. Ces discussions cherchent à répondre à la question de régiosélectivité de la cyclonickellation : on y démontre que cette réaction est gouvernée par les facteurs stériques, menant à la métallation préférablement (pour les substituants fluor) ou exclusivement (pour les substituants plus volumineux) aux carbones les moins encombrés, lorsque deux positions ortho sont disponibles, et que la réaction mène toujours à la formation de nickellacycles à 5 chainons. Ainsi, les phénols C3-substitués subissent la métallation au carbone C6, alors que les 1- et 2-naphtols subissent la nickellation aux positions C2 et C3, respectivement. Ces deux chapitres démontrent que la métallation peut avoir lieu sur des carbones qui possèdent déjà un voisin encombrant (F, OMe, benzo), menant à des structures relativement distordues, mais que la nickellation n’est pas produite dans les conditions standard au voisinage des substituants Me et Cl qui sont plus volumineux, ni au carbone C8 du 1-naphtol qui mènerait à un nickellacycle à 6 chainons. L’étude structurale permet de rationaliser les régiosélectivités observées, et les études par diverses méthodes RMN complètent la caractérisation de ces nouveaux composés. Le Chapitre 2 démontre que lorsque les sites potentiels de nickellation sont bloqués par des substituants ortho Me ou Ph, la réaction ne prend pas place sur ces substituants en raison de la formation de nickellacycles à 6 ou 7 chainons respectivement. Ceci met en lumière également l’impossibilité d’isoler les composés nickellés aux carbones sp³ des substituants ortho, et le Chapitre 4 démontre par des expériences d’échange H/D que la nickellation à ces positions n’est pas seulement thermodynamiquement défavorisée, mais qu’elle est aussi cinétiquement inexistante. Ce chapitre dévoile également les réactions qui sont observables à 80 °C sont radicalement accélérées à haute température (120 ou 160 °C), et que les produits de nickellation y sont thermodynamiquement stables. Le Chapitre 4 présente également une réaction de fonctionnalisation in situ des liens carbone-nickel de la phosphinite cyclonickellée dérivée du 1-naphthol. Dans cette réaction, qui se produit à haute température en absence de base, la bromophosphine Br-P(i-Pr)2 se génère in situ et permet l’insertion formelle d’un phosphènium [(i-Pr)2P]+ dans le lien carbone-nickel, menant à un complexe phosphine-phosphinite de type {κP,κP’-1-(i-Pr)2PO-2-naphtyl-P(i-Pr)2}NiBr2. Lorsque la position C2 du 1-naphtol est bloquée par un substituant Et, un genre similaire de fonctionnalisation à la position C8 est observé, menant à l’obtention de 8-(i-Pr)2P(O)-2-Et-1-naphtol, ainsi qu’à des sous-produits qui ont été identifiés et caractérisés. Cette réaction démontre l’accessibilité cinétique de la position C8 à haute température, mais démontre également l’instabilité du nickellaycle généré. Les conditions réactionnelles pour l’obtention des phosphinites nickellées dévoilées au Chapitre 2 (utilisant l’acétonitrile comme solvant) ont démontré une efficacité supérieure que celle présentée précédemment (dans le toluène). Ainsi, le Chapitre 3, également basé sur un article publié, cherche à décrire les aspects mécanistiques de cette cyclométallation et démontre que les espèces initialement présentes dans l’acétonitrile sont des adduits mono-phosphinites du nickel au contraire des espèces présentes dans le toluène. Cette étude démontre qu’une base externe est nécessaire pour conduire à l’isolation des composés nickellés, mais qu’elle n’est pas impliquée dans le mécanisme de métallation car la formation des liens C-Ni se produit réversiblement en absence de base. Des suivis cinétiques indiquent que la réaction est de premier ordre et qu’un excès de base ralentit la réaction en formant des espèces non réactives, et que les bases idéales sont fortes et peu coordonnantes. Une étude mécanistique expérimentale révèle que l’étape de nickellation est de nature électrophile (pente de Hammett ρ ≈ –4) et associative (ΔH⧧ = 18(1) kcal·mol–1 and ΔS⧧ = −27(4) cal·mol–1·K–1) et que le transfert de proton est l’étape limitante (kH/kD ≈ 11). Ces résultats sont appuyés par une étude computationnelle par DFT qui démontre que la dissociation d’un ligand Br- mène à une paire d’ions comme intermédiaire, depuis lequel la déprotonation est réalisée par l’anion Br- dans un mécanisme de type CMD. Les résultats de ces calculs théoriques permettent également d’appuyer la thèse d’un état fondamental triplet pour les espèces présentes avant la nickellation dans l’acétonitrile. Les études sur la régiosélectivité ont mené à un résultat surprenant : à la place de subir la nickellation C-H, la phosphinite dérivée du 2-vinylphénol subit une attaque nucléophile sur le groupe vinyle afin de donner un composé tridenté portant un lien Csp³-Ni. Le Chapitre 5 présente ainsi une nouvelle stratégie de préparation des composés pincers par des réactions de type Umpolung. Le ligand 2-vinylphényl-OP(i-Pr)2 réagit avec des amines et des phosphines portant au moins un proton, pour donner des complexes pinceurs de type 6,4-POCY-NiBr (Y = P, N). Ce chapitre dévoile l’étendue des composés qui peuvent être produits par cette méthode, et offre une caractérisation de ces composés par RMN, diffraction des rayons X et par électrochimie, afin de comparer leurs caractéristiques avec les autres pincers décrits dans la littérature. Enfin, alors que le Chapitre 6 présente quelques résultats additionnels reliés aux divers axes de recherche de cette thèse, le Chapitre 7 rappelle les grandes lignes des découvertes présentées aux Chapitres 2-5. Ce chapitre de conclusion générale présente également des perspectives basées sur les résultats de la thèse, et sur les quelques résultats préliminaires. Au menu : une discussion sur la relation entre régiosélectivité et la stabilité, des nouvelles stratégies de nickellation à étudier (à partir de liens carbone-halogène), la fonctionnalisation des liens C-Ni par des composés isolobaux aux phosphèniums et des stratégies pour la fonctionnalisation des oléfines dans les composés de type alcool.This thesis presents various aspects of the cyclonickelation of phosphinites Aryl-OP(i-Pr)2, as well as their potential in functionalization processes and applications in the preparation of new types of pincer-Ni complexes. Chapter 1 consists of a general introduction on the importance of the carbon-nickel bond in organometallic chemistry. Various strategies leading to C-Ni bonds in classical (monodentate) compounds, pincer complexes (tridentate), and cyclonickelated species (bi- and tridentate) are disclosed, including reactions implicating Ni0, de NiII ou de NiIV precursors. This chapter also presents the reactivity of species featuring C-Ni bonds C-Ni and underlines the reactivity of C-Ni bonds, especially in catalytic processes targeting C-H bonds functionalization, through the use of directing groups. Next, phosphinites are displayed as interesting directing groups in catalysis even though they have been used mostly with metals other than nickel. The last part of this chapter outlines the questions that are meant to be addressed in the next chapters. Chapters 2 and 4, based on published articles, display the isolation and characterization of dimeric complexes of the type [{κP,κC-(i-Pr)2POAr}Ni(μ-Br)]2 arising from the ortho-nickelation of phosphinites derived from substituted phenols and naphthols, as well as some of their acetonitrile or phosphinite adducts. These studies are meant to address the question of regioselectivity in the cyclonickelation. The results obtained prove that when two ortho sites are available for reactivity, the nickelation is governed by steric factors and leads to metalation preferably (in case of F substituents) or exclusively (in case of larger substituents) at the least hidered C-H bond; moreover, the nickelation always leads to 5-membered nickelacycles. Thus, C3-substituted phenols undergo nickelation at the C6 position, while 1- and 2-naphthols undergo nickelation at C2 and C3 positions, respectively. Together, Chapters 2 and 4 show that metalation can take place at the carbon next to a F-, MeO- or benzo substituent, but such nickelation at the hindered sites leads to distorted structures in the products. One the other hand, nickelation never occurs at carbons neighbouring the larger Me- or Cl- substituents, nor at the C8 position of 1-naphthol which would lead to a 6-membered nickelacycle. The structural study allows us to rationalize the observed regioselectivities, and NMR studies complete the characterization of these new compounds. Chapter 2 also reveals that when the ortho sites are blocked by Me or Ph functional groups, no nickelation takes places on these substituents due to the unfavored generation of 6- or 7-membered metallacycles, respectively. This finding also rationalizes why it has not been possible to isolate complexes arising from the nickelation at sp³ carbons of ortho substituents. This point is confirmed in the studies described in Chapter 4, which shows how H/D exchange experiments helped us prove that reactivity at these aliphatic C-H sites is disfavored not only thermodynamically, but also kinetically. This chapter also reveals that reactions observed at 80 °C can be accelerated dramatically at higher temperatures (120 or 160 °C), and that nickelated products are stable in these conditions. Chapter 4 also presents some examples of in situ functionalization of the C-Ni bonds in cyclonickelated 1-naphthyl phosphinites. Conducting these reactions in the absence of base at high temperatures allowed the in situ generation of bromoposphine, Br-P(i-Pr)2, that promotes the formal insertion of a phosphenium fragment [(i-Pr)2P]+ into the C-Ni bond, thus leading to a phosphine-phosphinite complex of Ni, of the following formula: {κP,κP’-1-(i-Pr)2PO-2-naphtyl-P(i-Pr)2}NiBr2. When the C2 position in the naphthyl phosphinite is blocked by an Et substituent, a similar functionalization occurs at the C8 position leading to 8-(i-Pr)2P(O)-2-Et-1-naphtol, along with by-products which have been identified and characterized. These findings demonstrated the kinetic accessibility of the C8 position at high temperatures, while proving the instability of the generated nickelacycle. The reaction conditions used for the syntheses of cyclonickelated phosphinites displayed in Chapter 2 (using acetonitrile as the solvent) have been proven more efficient than that previously reported (in toluene). Thus, Chapter 3, also based on a published article, describes the mechanistic aspects of the new procedure and reveals that acetonitrile generates more reactive species at the pre-nickelation stage, namely mono-phosphinite nickel adducts, as opposed to the bis-phosphinite nickel complexes observed in toluene. This study demonstrates that an external base is required for isolating the nickelated complexes, but that this base is not implicated in the metalation process, since the formation of the C-Ni bond occurs reversibly in the absence of base. Kinetic monitoring reveals that the reaction is 1st order and that an excess of base in fact slows down the rate by generating non-reactive species. Ideal bases for the nickelation are thus strong bases but weakly coordinating nucleophiles. An experiment-based mechanistic investigation shows that the nickelation is of electrophilic (Hammett slope ρ ≈ –4) and associative (ΔH⧧ = 18(1) kcal·mol–1 and ΔS⧧ = −27(4) cal·mol–1·K–1) nature, and that the proton transfer is rate limiting (kH/kD ≈ 11). These results are supported by a DFT-based computational study that points towards an ion pair formation that allows the dissociated Br- anion to capture the proton, in a CMD mechanism. The theoretical calculation also supported a triplet ground state in acetonitrile for the species present in the pre-nickelation mixture in acetonitrile. Regioselectivity studies of a phosphinite bearing an ortho-vinyl substituent led to a surprising finding: instead of undergoing C-H nickelation, the phosphinite derived from 2-vinylphenol is attacked by nucleophiles on the vinyl moiety and give a Ni complex featuring a tridentate pincer-type ligand with a central Csp³-Ni bond. Chapter 5 thus discloses a new Umpolung-based strategy leading to new pincer complexes. Reaction of the ligand 2-vinylphenyl-OP(i-Pr)2 with primary or secondary amines and phosphines produces novel pincer-Ni complexes of the type 6,4-POCsp3Y-NiBr (Y = P, N). This chapter discloses the variety of new complexes that can be prepared by this new synthetic strategy. The characterisation of the new complexes by NMR, XRD and electrochemical analysis allowed us to compare their structural and redox properties to pincer-Ni complexes reported in the literature. While Chapter 6 discloses additional results related to various research axes of this thesis, Chapter 7 recalls the main findings revealed in Chapters 2-5. This conclusion also discloses research perspectives based on the results presented in this thesis, as well as phosphinite-related preliminary results gathered during my Ph. D. studies. The main proposed ideas touch on the following aspects: (a) the relationship between regioselectivity and stability towards functionalization; (b) new nickelation strategies based on the metalation of carbon-halogen bonds; (c) C-Ni functionalization by isolobal compounds to phosphenium ions; and (d) strategies towards the functionalization of alcohols bearing alkene moieties

Development and validation of a postmortem radiological alteration index: the RA-Index

This study aimed to derive an index quantifying the state of alteration of cadavers by quantifying the presence of gas in the body using postmortem multidetector computed tomography (MDCT) imaging, and to validate the index by defining its sensitivity and specificity. The RA (radiological alteration)-index was derived from postmortem MDCT data from 118 nontraumatically deceased people. To validate the index, 100 additional scanned bodies (50 % traumatically deceased) were retrospectively examined by two independent observers. Presence of gas at 82 sites was assessed by a radiologist, whereas a forensic pathologist only investigated the seven sites used for the RA-index. The RA-index was highly correlated to the overall presence of gas in all 82 sites (R2 = 0.98 in the derivation set and 0.85 in the validation set). Semiquantitative evaluation of gas presence in each site showed moderate reliability (Cohen's kappa range, 0.41-0.78); nevertheless, the overall RA-index was very reliable (ICC2,1 = 0.95; 95 % CI 0.92-0.96). Examiner using the RA-index detected heart cavities full of gas with a sensitivity of 100 % (95 % CI 51.7-100) and a specificity of 98.8 % (92.6-99.9). We conclude that determining the presence of gas at seven sites is a valid means to measure the distribution of gas due to cadaveric alteration in the entire body. The RA-index is rapid, easy-to-use, and reliable for nonexperienced users, and it is a valid method to suspect the normal presence of gas from cadaveric alteration. MDCT can be used to screen for gas embolism and to give indications for gas composition analysis (gas chromatography

Two types of all-optical magnetization switching mechanisms using femtosecond laser pulses

Magnetization manipulation in the absence of an external magnetic field is a topic of great interest, since many novel physical phenomena need to be understood and promising new applications can be imagined. Cutting-edge experiments have shown the capability to switch the magnetization of magnetic thin films using ultrashort polarized laser pulses. In 2007, it was first observed that the magnetization switching for GdFeCo alloy thin films was helicity-dependent and later helicity-independent switching was also demonstrated on the same material. Recently, all-optical switching has also been discovered for a much larger variety of magnetic materials (ferrimagnetic, ferromagnetic films and granular nanostructures), where the theoretical models explaining the switching in GdFeCo films do not appear to apply, thus questioning the uniqueness of the microscopic origin of all-optical switching. Here, we show that two different all-optical switching mechanisms can be distinguished; a "single pulse" switching and a "cumulative" switching process whose rich microscopic origin is discussed. We demonstrate that the latter is a two-step mechanism; a heat-driven demagnetization followed by a helicity-dependent remagnetization. This is achieved by an all-electrical and time-dependent investigation of the all-optical switching in ferrimagnetic and ferromagnetic Hall crosses via the anomalous Hall effect, enabling to probe the all-optical switching on different timescales.Comment: 1 page, LaTeX; classified reference number