Spectroscopic analysis of terrestrial analogues for the interpretation of surface composition of rocky bodies in the solar system. Effects of mineral mixing and particle size. Applications to moon, mars and implications for mercury.

Among the Solar System’s bodies, Moon, Mercury and Mars are at present, or have been in the recent years, object of space missions aimed, among other topics, also at improving our knowledge about surface composition. Between the techniques to detect planet’s mineralogical composition, both from remote and close range platforms, visible and near-infrared reflectance (VNIR) spectroscopy is a powerful tool, because crystal field absorption bands are related to particular transitional metals in well-defined crystal structures, e.g., Fe2+ in M1 and M2 sites of olivine or pyroxene (Burns, 1993). Thanks to the improvements in the spectrometers onboard the recent missions, a more detailed interpretation of the planetary surfaces can now be delineated. However, quantitative interpretation of planetary surface mineralogy could not always be a simple task. In fact, several factors such as the mineral chemistry, the presence of different minerals that absorb in a narrow spectral range, the regolith with a variable particle size range, the space weathering, the atmosphere composition etc., act in unpredictable ways on the reflectance spectra on a planetary surface (Serventi et al., 2014). One method for the interpretation of reflectance spectra of unknown materials involves the study of a number of spectra acquired in the laboratory under different conditions, such as different mineral abundances or different particle sizes, in order to derive empirical trends. This is the methodology that has been followed in this PhD thesis: the single factors previously listed have been analyzed, creating, in the laboratory, a set of terrestrial analogues with well-defined composition and size. The aim of this work is to provide new tools and criteria to improve the knowledge of the composition of planetary surfaces. In particular, mixtures composed with different content and chemistry of plagioclase and mafic minerals have been spectroscopically analyzed at different particle sizes and with different mineral relative percentages. The reflectance spectra of each mixture have been analyzed both qualitatively (using the software ORIGIN®) and quantitatively applying the Modified Gaussian Model (MGM, Sunshine et al., 1990) algorithm. In particular, the spectral parameter variations of each absorption band have been evaluated versus the volumetric FeO% content in the PL phase and versus the PL modal abundance. This delineated calibration curves of composition vs. spectral parameters and allow implementation of spectral libraries. Furthermore, the trends derived from terrestrial analogues here analyzed and from analogues in the literature have been applied for the interpretation of hyperspectral images of both plagioclase-rich (Moon) and plagioclase-poor (Mars) bodies.

Ideological Closure : Drug Prevention in a Post-political Society

The aim of this thesis is to critically examine drug prevention as a field of problematizations  – how drug prevention becomes established as a political technology within this field, how it connects to certain modes of governance, how and under which conditions it constitutes it’s problematic, the questions it asks,  it´s implications in terms of political participation and representation, the various bodies of knowledge through which it constitutes the reality upon which it acts, the limits it places on ways of being, questioning, and talking  in the world. The main analyses have been conducted in four separate but interrelated articles. Each article addresses a specific dimension of drug prevention in order to get a grasp of how this field is organized. Article 1 examines the shift that has occurred in the Swedish context during the period 1981–2011 in how drugs have been problematized, what knowledge has grounded the specific modes of problematization and which modes of governance this has enabled. In article 2, the currently dominant scientific discipline in the field of drug prevention – prevention science – is critically examined in terms of how it constructs the “drug problem” and the underlying assumptions it carries in regard to reality and political governance. Article 3 addresses the issue of communities’ democratic participation in drug prevention efforts by analyzing the theoretical foundations of the Communities That Care prevention program. The article seeks to uncover how notions of community empowerment and democratic participation are constructed, and how the “community” is established as a political entity in the program. The fourth and final article critically examines the Swedish Social and Emotional Training (SET) program and the political implications of the relationship the program establishes between the subject and emotions. The argument is made that, within the field of drug prevention, questions of political values and priorities in a problematic way are decoupled from the political field and pose a significant problem in terms of the possibilities to engage in democratic deliberation. Within this field of problematizations it becomes impossible to mobilize a politics against social injustice, poverty and inequality. At the same time, the scientific grounding of this mode of governing the drug “problem” acts to naturalize a specific – highly political – way of engaging with drugs.

Size frequency distribution of the β-amyloid (aβ) deposits in dementia with Lewy bodies with associated Alzheimer’s disease pathology

The objective is to study beta-amyloid (Abeta) deposition in dementia with Lewy bodies (DLB) with Alzheimer's disease (AD) pathology (DLB/AD). The size frequency distributions of the Abeta deposits were studied and fitted by log-normal and power-law models. Patients were ten clinically and pathologically diagnosed DLB/AD cases. Size distributions had a single peak and were positively skewed and similar to those described in AD and Down's syndrome. Size distributions had smaller means in DLB/AD than in AD. Log-normal and power-law models were fitted to the size distributions of the classic and diffuse deposits, respectively. Size distributions of Abeta deposits were similar in DLB/AD and AD. Size distributions of the diffuse deposits were fitted by a power-law model suggesting that aggregation/disaggregation of Abeta was the predominant factor, whereas the classic deposits were fitted by a log-normal distribution suggesting that surface diffusion was important in the pathogenesis of the classic deposits.

Laminar distribution of β-amyloid deposits in dementia with Lewy bodies and in Alzheimer's disease

This study tested whether the laminar distribution of the β-amyloid (Aβ) deposits in dementia with Lewy bodies (DLB) cases with significant Alzheimer's disease (AD) pathology (DLB/AD) was similar to "pure" AD. In DLB/AD, the maximum density of the diffuse and primitive deposits occurred either in the upper laminae or a bimodal distribution was present with density peaks in the upper and lower laminae. A bimodal distribution of the classic Aβ deposits was also observed. Compared with AD, DLB/AD cases had fewer primitive deposits relative to the diffuse and classic deposits; the primitive deposits exhibited a bimodal distribution more frequently, and the diffuse deposits occurred more often in the upper laminae. These results suggest that Aβ pathology in DLB/AD may not simply represent the presence of associated AD. © 2006 Sage Publications.

Beta-amyloid deposition in the temporal lobe of patients with dementia with Lewy bodies:Comparison with non-demented cases and Alzheimer's disease

β-Amyloid (Aβ) deposition in regions of the temporal lobe in patients with dementia with Lewy bodies (DLB) was compared with elderly, non-demented (ND) cases and with Alzheimer's disease (AD). The distribution, density and clustering patterns of diffuse, primitive and classic Aβ deposits were similar in 'pure' DLB and ND cases. The distribution of Aβ deposits and the densities of the diffuse and primitive deposits were similar in 'mixed' DLB/AD cases compared with AD. However, the density of the classic deposits was significantly lower in DLB/AD compared with AD. In addition, the primitive Aβ deposits occurred more often in small, regularly spaced clusters in the tissue and less often in a single large cluster in DLB/AD compared with 'pure' AD. These results suggest that pure DLB and AD are distinct disorders which can coexist in some patients. However, the Aβ pathology of DLB/AD cases is not identical to that observed in patients with AD alone. (C) 2000 S. Karger AG, Basel.

Clustering of Pick bodies in the dentate gyrus in Pick's disease

In patients with Pick's disease (PD), high densities of tau positive Pick bodies (PB) have been observed within the granule cell layer of the dentate gyrus. This study investigated the spatial patterns of PB along the granule cell layer in coronal sections of the hippocampus in eight patients with PD. In all patients, there was evidence of clustering of PB within the granule cell layer; however, there was considerable variation in the pattern of clustering. In five patients, the clusters of PB were regularly distributed along the dentate gyms, and in two of these patients, the smaller clusters were aggregated into larger superclusters. In three patients, a single large cluster of PB, more than 1200 μm in diameter, was present. Clustering of PB may reflect a primary degenerative process within the granule cells or the degeneration of pathways that project to the dentate gyrus.