Procedures of quality control and data analysis of multi-site ground-based observations for the absolute flux calibration of Gaia

The Gaia space mission is a major project for the European astronomical community. As challenging as it is, the processing and analysis of the huge data-flow incoming from Gaia is the subject of thorough study and preparatory work by the DPAC (Data Processing and Analysis Consortium), in charge of all aspects of the Gaia data reduction. This PhD Thesis was carried out in the framework of the DPAC, within the team based in Bologna. The task of the Bologna team is to define the calibration model and to build a grid of spectro-photometric standard stars (SPSS) suitable for the absolute flux calibration of the Gaia G-band photometry and the BP/RP spectrophotometry. Such a flux calibration can be performed by repeatedly observing each SPSS during the life-time of the Gaia mission and by comparing the observed Gaia spectra to the spectra obtained by our ground-based observations. Due to both the different observing sites involved and the huge amount of frames expected (≃100000), it is essential to maintain the maximum homogeneity in data quality, acquisition and treatment, and a particular care has to be used to test the capabilities of each telescope/instrument combination (through the “instrument familiarization plan”), to devise methods to keep under control, and eventually to correct for, the typical instrumental effects that can affect the high precision required for the Gaia SPSS grid (a few % with respect to Vega). I contributed to the ground-based survey of Gaia SPSS in many respects: with the observations, the instrument familiarization plan, the data reduction and analysis activities (both photometry and spectroscopy), and to the maintenance of the data archives. However, the field I was personally responsible for was photometry and in particular relative photometry for the production of short-term light curves. In this context I defined and tested a semi-automated pipeline which allows for the pre-reduction of imaging SPSS data and the production of aperture photometry catalogues ready to be used for further analysis. A series of semi-automated quality control criteria are included in the pipeline at various levels, from pre-reduction, to aperture photometry, to light curves production and analysis.

Qualitative and absolute quantitative studies of the cell-nanoparticle interaction

This thesis focused on the polymer’s influence on the interaction of polymeric NPs with epithelial cells. Furthermore, the measurement of single submicron nanoparticles in a commercially available flow cytometer was established, to provide a new method in the toolbox for nanoparticle-cell studies. This gave way to develop a routine for the absolute quantification of intracellular NPs via flow cytometry. rnThe cellular uptake of poly(methyl methacrylate) (PMMA), polystyrene (PS) and poly(L-lactide) (PLLA) nanoparticles was investigated via flow cytometry. PLLA-NPs were internalized the most efficiently. But upon co-incubation of PS and PLLA particles with cells, the two particles mutually influenced their uptake, slightly shifting the relative uptake efficiencies. This phenomenon should be based on specific properties of the different polymer materials. The findings indicated a competition (which is strongly influenced by properties of the respective polymeric material) for the uptake into the cells, allegedly due to competition for specific coatings with serum components that enhances the NPs’ cellular uptake. The fluorescence of single 150 nm particles was determined with a benchtop cytometer, breaching the machine’s detection limit but yielding precise NP fluorescence standardization factors. Up to now, these standardization factors are mostly determined by spectroscopic analysis of the particles’ dye content. Finally a flow cytometric routine for absolute particle counting in cells was devised. This quantitation revealed a low uptake efficiency for un-functionalized PMMA NPs of less than 150 NPs (approx. 0,001 % of added) per cell.rn

Absolute Hodge cycles and Deligne's principle b

I cicli di Hodge assoluti sono stati utilizzati da Deligne per dividere la congettura di Hodge in due sotto-congetture. La prima dice che tutte le classi di Hodge su una varietà complessa proiettiva liscia sono assolute, la seconda che le classi assolute sono algebriche. Deligne ha dato risposta affermativa alla prima sottocongettura nel caso delle varietà abeliane. La dimostrazione si basa su due teoremi, conosciuti rispettivamente come Principio A e Principio B. In questo lavoro vengono presentate la teoria delle classi di Hodge assolute e la dimostrazione del Principio B.

Atropisomeric xanthines: Synthesis, stereodynamics and absolute configuration

During the thesis period a new class of atropisomeric xanthine derivatives has been studied. We decided to focus our attention on these purine bases because of their various biological activities, that could play an important role in the discovery of new bioactive atropisomers. The synthesized compounds bear an Aryl-N chiral axis in position 1 of the xanthine scaffold, around which the rotation is prevented by the presence of bulky ortho substituents. Through a retro synthetic analysis we synthesized three atropisomeric structures bearing in position 1 of the purine scaffold respectively an o-tolyl, o-nitrophenyl and a 1-naphthyl group. The conformational studies by DFT simulations showed that the interconversion energy barrier between the two available skewed conformations is higher enough to obtain thermally stable atropisomers. After the separation of the atropisomers, the experimental energy of interconversion was investigated by means of kinetic studies following the thermal racemization process using an enantioselective HPLC column. The absolute configuration of each atropisomer was assigned by experimental ECD analysis and TD-DFT simulations of the ECD spectra.

Right ventricular absolute myocardial blood flow in complex congenital heart disease

A consequence in patients with d-transposition of the great arteries (d-TGA) and tetralogy of Fallot (TOF) is right ventricular hypertrophy (RVH) and right ventricular failure. Myocardial contrast echocardiography (MCE) permits the determination of the myocardial microvascular density reflected by the relative myocardial blood volume (rBV; ml/ml). This study was conducted to elucidate the relationship between RVH and myocardial microvascular changes by quantitative MCE in patients with d-TGA and TOF.

Absolute pKa Determinations for Substituted Phenols

The CBS-QB3 method was used to calculate the gas-phase free energy difference between 20 phenols and their respective anions, and the CPCM continuum solvation method was applied to calculate the free energy differences of solvation for the phenols and their anions. The CPCM solvation calculations were performed on both gas-phase and solvent-phase optimized structures. Absolute pKa calculations with solvated phase optimized structures for the CPCM calculations yielded standard deviations and root-mean-square errors of less than 0.4 pKa unit. This study is the most accurate absolute determination of the pKa values of phenols, and is among the most accurate of any such calculations for any group of compounds. The ability to make accurate predictions of pKa values using a coherent, well-defined approach, without external approximations or fitting to experimental data, is of general importance to the chemical community. The solvated phase optimized structures of the anions are absolutely critical to obtain this level of accuracy, and yield a more realistic charge separation between the negatively charged oxygen and the ring system of the phenoxide anions.

Absolute pitch and planum temporale

An increased leftward asymmetry of the planum temporale (PT) in absolute-pitch (AP) musicians has been previously reported, with speculation that early exposure to music influences the degree of PT asymmetry. To test this hypothesis and to determine whether a larger left PT or a smaller right PT actually accounts for the increased overall PT asymmetry in AP musicians, anatomical magnetic resonance images were taken from a right-handed group of 27 AP musicians, 27 nonmusicians, and 22 non-AP musicians. A significantly greater leftward PT asymmetry and a significantly smaller right absolute PT size for the AP musicians compared to the two control groups was found, while the left PT was only marginally larger in the AP group. The absolute size of the right PT and not the left PT was a better predictor of music group membership, possibly indicating “pruning” of the right PT rather than expansion of the left underlying the increased PT asymmetry in AP musicians. Although early exposure to music may be a prerequisite for acquiring AP, the increased PT asymmetry in AP musicians may be determined in utero, implicating possible genetic influences on PT asymmetry. This may explain why the increased PT asymmetry of AP musicians was not seen in the group of early beginning non-AP musicians.

Memory for the absolute pitch of familiar songs

Four experiments were conducted to examine the ability of people without "perfect pitch" to retain the absolute pitch offamiliar tunes. In Experiment 1, participants imagined given tunes, and then hummed their first notes four times either between or within sessions. The variability of these productions was very low. Experiment 2 used a recognition paradigm, with results similar to those in Experiment 1 for musicians, but with some additional variability shown for unselected subjects. In Experiment 3, subjects rated the suitability ofvarious pitches to start familiar tunes. Previously given preferred notes were rated high, as were notes three or four semitones distant from the preferred notes, but not notes one or two semitones distant. In Experiment 4, subjects mentally transformed the pitches of familiar tunes to the highest and lowest levels possible. These experiments suggest some retention of the absolute pitch of tunes despite a paucity of verbal or visual cues for the pitch.

A Test of Absolute Numerousness Judgments in Lion-Tailed Macaques (Macaca Silenus)

Numerous studies have shown that animals have a sense of quantity and can distinguish between relative amounts. The concepts of relative numerousness, estimation, and subitizing are well established in species as diverse as chimpanzees and salamanders. Mobile animals have practical use for an understanding of number in common situations such as predation, mating, and competition. However, the ability to identify discrete quantities has only been firmly established in humans. The purpose of this study was to test for such “absolute numerousness” judgments in three lion-tailed macaques (Macaca silenus), a non-human primate. The three macaques tested had previously been trained on a computerized matchto- sample (MTS) task using geometric shapes. In this study, they were introduced to a MTS task containing a numerical cue, which required the monkeys to match stimuli containing either one or two items for rewards. If monkeys were successful at the initial matching task, they were tested with stimuli in which the position of the items and then the surface area of the items was controlled. If the monkeys could match successfully without using these non-numerical cues, they would demonstrate the capability to make absolute numerousness judgments. None of the monkeys matched successfully using the numerical cue, so no evidence of absolute numerosity was found. Each macaque progressed through the experiment in an individualized manner, attempting a variety of strategies to obtain rewards. These included side preferences and an alternating-side strategy that were unrelated to the numerical cues in the stimuli. When it became clear that the monkeys were not matching based on a stimulus-based cue, they were tested again on matching geometric shapes. All three macaques stopped using their alternate strategies and were able to match shapes successfully, demonstrating that they were still capable of completing the matching task. The data suggest that the monkeys could not transfer this ability to the numerical stimuli. This indicates that the macaques lack a sense of exact quantity, or that they could not recognize the numerical cues in the stimuli as being relevant to the task.