94 research outputs found

    Atomic Disorder in Fossil Tooth and Bone Mineral: An FTIR Study Using the Grinding Curve Method

    Get PDF
    Bone and tooth mineral generally undergo diagenetic changes. These changes in the carbonate hydroxyapatite structure and composition can affect the signals embedded in the mineral phase, such as migration behavior, age of the specimen and the reconstruction of past environments. Mineral preservation state can be assessed using infrared spectroscopy which provides information on crystal disorder at the atomic level and mineral composition. Here we present a new approach to evaluate carbonate hydroxyapatite atomic disorder using infrared spectroscopy and the standard KBr sample mounting method. We show that by repeated grinding of the sample and then plotting the infrared splitting factor against the width of the major phosphate absorption peak after each grinding, grinding curves with well defined trend lines can be obtained. The offsets between curves reflect differences in atomic disorder. We show that grinding curve offsets can be used to evaluate the state of preservation of bone, dentine and enamel mineral.Les os et les dents subissent gĂ©nĂ©ralement des changements diagĂ©nĂ©tiques. Ces changements de la structure et de la composition de l’hydroxyapatite carbonatĂ©e peuvent affecter les signaux inclus dans la phase minĂ©rale, tels que les comportements de migration, l’ñge des spĂ©cimens ou la reconstitution des environnements passĂ©s. L’état de prĂ©servation de la phase minĂ©rale peut ĂȘtre dĂ©terminĂ© par la spectromĂ©trie infrarouge qui fournit des informations sur le dĂ©sordre structural et sur la composition du minĂ©ral. Dans cette Ă©tude, nous prĂ©sentons une nouvelle approche permettant d’évaluer le dĂ©sordre cristallin en utilisant la spectromĂ©trie infrarouge. Nous montrons ici qu’un broyage rĂ©pĂ©tĂ© de l’échantillon et la reprĂ©sentation graphique des valeurs de splitting factor et de la largeur Ă  mi-hauteur de la principale bande d’absorption des phosphates aprĂšs chaque broyage, peut permettre de dĂ©finir des courbes de broyage avec des tendances bien dĂ©finies. Un dĂ©calage entre ces courbes reflĂšte des diffĂ©rences de dĂ©sorganisation Ă  l’échelle atomique

    Good health checks according to the general public; Expectations and criteria: A focus group study

    Get PDF
    Background: Health checks or health screenings identify (risk factors for) disease in people without a specific medical indication. So far, the perspective of (potential) health check users has remained underexposed in discussions about the ethics and regulation of health checks. Methods: In 2017, we conducted a qualitative study with lay people from the Netherlands (four focus groups). We asked what participants consider characteristics of good and bad health checks, and whether they saw a role for the Dutch government. Results: Participants consider a good predictive value the most important characteristic of a good health check. Information before, during and after the test, knowledgeable and reliable providers, tests for treatable (risk factors for) disease, respect for privacy, no unnecessary health risks and accessibility are also mentioned as criteria for good health checks. Participants make many assumptions about health check offers. They assume health checks provide certainty about the presence or absence of disease, that health checks offer opportunities for health benefits and that the privacy of health check data is guaranteed. In their choice for provider and test they tend to rely more on heuristics than information. Participants trust physicians to put the interest of potential health check users first and expect the Dutch government to intervene if providers other than physicians failed to do so by offering tests with a low predictive value, or tests that may harm people, or by infringing the privacy of users. Conclusions: Assumptions of participants are not always justified, but they may influence the choice to participate. This is problematic because choices for checks with a low predictive value that do not provide health benefits may create uncertainty and may cause harm to health; an outcome diametrically opposite to the one intended. Also, this may impair the relationship of trust with physicians and the Dutch government. To further and protect autonomous choice and to maintain trust, we recommend the following measures to timely adjust false expectations: advertisements that give an accurate impression of health check offers, and the installation of a quality mark

    Interpersonal and affective dimensions of psychopathic traits in adolescents : development and validation of a self-report instrument

    Get PDF
    We report the development and psychometric evaluations of a self-report instrument designed to screen for psychopathic traits among mainstream community adolescents. Tests of item functioning were initially conducted with 26 adolescents. In a second study the new instrument was administered to 150 high school adolescents, 73 of who had school records of suspension for antisocial behavior. Exploratory factor analysis yielded a 4-factor structure (Impulsivity α = .73, Self-Centredness α = .70, Callous-Unemotional α = .69, and Manipulativeness α = .83). In a third study involving 328 high school adolescents, 130 with records of suspension for antisocial behaviour, competing measurement models were evaluated using confirmatory factor analysis. The superiority of a first-order model represented by four correlated factors that was invariant across gender and age was confirmed. The findings provide researchers and clinicians with a psychometrically strong, self-report instrument and a greater understanding of psychopathic traits in mainstream adolescents

    Shared neural correlates for building phrases in signed and spoken language

    Get PDF
    Abstract Research on the mental representation of human language has convincingly shown that sign languages are structured similarly to spoken languages. However, whether the same neurobiology underlies the online construction of complex linguistic structures in sign and speech remains unknown. To investigate this question with maximally controlled stimuli, we studied the production of minimal two-word phrases in sign and speech. Signers and speakers viewed the same pictures during magnetoencephalography recording and named them with semantically identical expressions. For both signers and speakers, phrase building engaged left anterior temporal and ventromedial cortices with similar timing, despite different linguistic articulators. Thus the neurobiological similarity of sign and speech goes beyond gross measures such as lateralization: the same fronto-temporal network achieves the planning of structured linguistic expressions

    Geslacht en Arbeidsduur

    No full text

    The association between psychopathy and delinquency in juveniles: A three-level meta-analysis

    Get PDF
    Background: Psychopathy has repeatedly been linked with delinquency and criminal recidivism of adults. With the increase of studies examining psychopathic traits in juveniles, it is important to also study this association in juveniles to increase the effectiveness of preventive interventions for juvenile delinquency. Purpose: The primary aim of the present meta-analysis was to examine the association between psychopathic traits and delinquency in juveniles. The second aim was to examine which factors (i.e., type of delinquency, type of psychopathic trait, and other study- and participant characteristics,) moderate the association between psychopathy and juvenile delinquent behavior. Method: The data were analyzed in three-level meta-analytic models. Results: In total, 87 studies were included, which used 74 independent samples and reported on 358 effect sizes. Psychopathy was moderately and positively associated with juvenile delinquency (r = .24, p < .0001). This overall association was not influenced by type of delinquency. However, stronger effect sizes were found for impulsivity traits than for callous unemotional traits. Conclusion: Psychopathy in juveniles is associated with current and future offense behavior. Therefore, assessing psychopathy in juveniles is important for strengthening intervention efforts targeting juvenile delinquency

    The pigments of the frigidarium in the Sarno Baths, Pompeii: Identification, stratigraphy and weathering

    No full text
    In the present research is used a multi-analytical approach to study the wall paintings from the Sarno Baths, located in the southern part of Pompeii. In particular the investigation is focused on the frescos of the frigidarium, though a few samples from other rooms were also analysed. Twenty wallpaintings fragments were analysed by laser scanning confocal microscopy (LSCM), optical microscopy (OM), micro-Raman, scanning electron microscope with energy dispersive spectrometry (SEM-EDS), portable X-ray fluorescence spectrometry (p-XRF) and X-ray powder diffraction (XRPD). The XRPD data were used for the mineralogical semi-quantitative phase analyses (SQPA) and the estimation of the hematite crystals size. The obtained data allow the identification of the pigments and the techniques used, and address new question such as whether talc and aragonite were used routinely in the formulation of pigments. The chemical composition of red and yellow pigments is also discussed and compared with data available from the recent literature. The wall paintings are badly preserved and weathering products occur on the pictorial surface. Eight samples of efflorescence salts and patinas were analysed by XRPD: all the samples are composed mainly by alkali sulphates. The systematic difference between the salts present on the northern and the western walls is likely related to the materials inserted during the 19th century restauration
    • 

    corecore