280 research outputs found

    From MALDI-TOF Mass Spectrometry to Soft-Landing for Electronics

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    Within this PhD thesis matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been used as a reliable tool for the quantitative characterization of giant molecules, such as alkyl substituted and unsubstituted large polycyclic aromatic hydrocarbons (PAH), which cannot be characterized by conventional analytic techniques due to their lack of solubility. The use of the MALDI solvent-free technique for the sample preparation and the application of the standard addition method have allowed the quantitative characterization of synthetic PAH mixtures. The knowledge, acquired by studying these representative systems, has been then transferred to the quantitative analyses of complex and slightly soluble natural PAH mixtures, such as mesophase pitch. Moreover, the possibility to ionize intractable and insoluble molecules via mass spectrometry has been recognized to be not only a powerful analytical method, but also to represent a unique change to handle giant aromatic systems and to deposit them on a surface for further investigations, in a process, which is defined as “soft-landing”. Within this novel deposition technique, ions of the desired analytes or analyte mixtures are generated by means of an MS ionization source, discriminated by their different mass to charge ratios via a mass analyzer and landed with retention of their structure on a desired surface. This soft-deposition is guaranteed by the use of decelerating potentials, which have in this work been recognized to influence the final packing of the analyte molecules reaching the landing surface. For a more detailed study of the electrical field action on disc-like and rod-like molecules, soft-landing-independent experiments have been additionally carried out. As a result unidirectionally ordered films of the analyte molecules have been obtained due to the application of an external electrical strength. This versatile alignment technique has then been used for obtaining ordered layers of semiconducting materials for the fabrication of organic field effect transistors (OFET) with improved performances.“From MALDI TOF Mass Spectrometry to Soft Landing for Electronics” Anna Maria Cristadoro Zusammenfassung Im Rahmen dieser Doktorarbeit wurden Methoden entwickelt, um unlösliche Stoffe mittels MALDI-TOF-Massenspektrometrie zu quantifizieren, als Modellsysteme dienten dabei Mischungen aus verschiedenen polyzyklischen aromatischen Kohlenwasserstoffe (PAH). Die Kombination aus einer lösungsmittelfreien Probenvorbereitung und der Verwendung einer Standardadditionsreihe zeigte sich dabei als überaus geeignet, um neben diesen Modellsystemen auch natürlich vorkommende Schlacken quantitativ zu charakterisieren. Der zweite Teil der Arbeit beschäftigt sich mit den Ionisierungseigenschaften von unlöslichen Polymeren und niedermolekularen Verbindungen, welche Anwendungen in der organischen Elektronik finden. Hierbei zeigte sich, dass die Ionisierbarkeit dieser Materialien ausgenutzt werden kann, um einzelne Molekülisotope dieser Stoffe gezielt auf Oberflächen anzureichern. Die als „Soft-Landing“ bekannte Methode basiert dabei auf der Trennung der ionisierten Moleküle in einem Sektorfeld und anschließender Deposition auf einem geeigneten Substrat. Durch das Anlegen eines elektrischen Feldes nahe der Oberfläche konnte dabei sichergestellt werden, dass die anzureichernden Moleküle während der Depostion nicht fragmentieren. Zudem wurde gefunden, dass die Überstruktur, welche die Moleküle auf der Oberfläche ausbilden, durch die Charakteristik des angelegten Feldes beeinflusst werden kann. Als Ergebnis konnten dadurch unidirektional ausgerichtete und halbleitende Polymerfilme erzeugt werden, welche ihre Anwendungsmöglichkeiten im Aufbau von organischen Feldeffekttransitoren finden

    Children of Foster Care: Elevating their Voices

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    The purpose of this paper was to discuss how through research and an internship with Douglas County Child Welfare, elevating children â„¢s voices in decisions of placement is a vital component of child welfare reform today. This paper examines some of the negative outcomes of the foster care system on children who age out of the system. The negative impact further deteriorates children â„¢s self esteem and increases the occurrence of homelessness and incarceration in our society. The internship further validated the difficulty inherent in including children in decisions of placements and the importance of allowing extra time, planning and changing mind sets in order to elevate the voice of one of the most vulnerable segments of our population, children of foster care

    Letter, 1949 March 25, from A. J. Cristadoro to Carson Robison

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    1 page, Cristadoro is an employee of the MGM Record Division for the Rado Specialty Corporation

    Letter, 1949 April 29, from A. J. Cristadoro to Carson Robison

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    1 page, Cristadoro is an employee of theMGM Record Division for the Rado Specialty Corporation

    Nonequilibrium stationary states with ratchet effect

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    An ensemble of particles in thermal equilibrium at temperature TT, modeled by Nos\`e-Hoover dynamics, moves on a triangular lattice of oriented semi-disk elastic scatterers. Despite the scatterer asymmetry a directed transport is clearly ruled out by the second law of thermodynamics. Introduction of a polarized zero mean monochromatic field creates a directed stationary flow with nontrivial dependence on temperature and field parameters. We give a theoretical estimate of directed current induced by a microwave field in an antidot superlattice in semiconductor heterostructures.Comment: 4 pages, 5 figures (small changes added

    Do Humans and Deep Convolutional Neural Networks Use Visual Information Similarly for the Categorization of Natural Scenes?

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    The investigation of visual categorization has recently been aided by the introduction of deep convolutional neural networks (CNNs), which achieve unprecedented accuracy in picture classification after extensive training. Even if the architecture of CNNs is inspired by the organization of the visual brain, the similarity between CNN and human visual processing remains unclear. Here, we investigated this issue by engaging humans and CNNs in a two-class visual categorization task. To this end, pictures containing animals or vehicles were modified to contain only low/high spatial frequency (HSF) information, or were scrambled in the phase of the spatial frequency spectrum. For all types of degradation, accuracy increased as degradation was reduced for both humans and CNNs; however, the thresholds for accurate categorization varied between humans and CNNs. More remarkable differences were observed for HSF information compared to the other two types of degradation, both in terms of overall accuracy and image-level agreement between humans and CNNs. The difficulty with which the CNNs were shown to categorize high-passed natural scenes was reduced by picture whitening, a procedure which is inspired by how visual systems process natural images. The results are discussed concerning the adaptation to regularities in the visual environment (scene statistics); if the visual characteristics of the environment are not learned by CNNs, their visual categorization may depend only on a subset of the visual information on which humans rely, for example, on low spatial frequency information

    Adaptive Preference Formation & Autonomy: Moving towards Respect

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    First lines of the Introduction (as abstract not provided): This thesis seeks to primarily answer the following question: are adapted preferences autonomous? In pursuing the answer of this question, I am unsurprisingly faced with two importantly related queries: firstly, what actually is adaptive preference formation? And secondly, what kind of theory of autonomy is correct and why? In the spirit of question answering, the first chapter of this thesis seeks to provide a more robust account of adaptive preference formation (herein APF), a theory which states that the preferences held by an agent can be subconsciously causally produced by the restriction of options. Through an examination of Jon Elster’s original account of the concept, and a consideration of Amartya Sen and Martha Nussbaum’s contemporary interpretations of Elster’s account, I intend to flesh out the mechanics of APF, considering the necessary and sufficient conditions for APF. This section aims to solidify the descriptive literature of APF, with a focus on differentiating the process from other similar concepts such as character planning and internalised oppression (herein IO). Ultimately, I conclude with a variation of Elster’s account and produce my own examples of agents who hold adapted preferences (herein AP)

    Short-Term Forecasting of GDP Using Large Monthly Datasets: A Pseudo Real-Time Forecast Evaluation Exercise

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    This paper evaluates different models for the short-term forecasting of real GDP growth in ten selected European countries and the euro area as a whole. Purely quarterly models are compared with models designed to exploit early releases of monthly indicators for the nowcast and forecast of quarterly GDP growth. Amongst the latter, we consider small bridge equations and forecast equations in which the bridging between monthly and quarterly data is achieved through a regression on factors extracted from large monthly datasets. The forecasting exercise is performed in a simulated real-time context, which takes account of publication lags in the individual series. In general, we find that models that exploit monthly information outperform models that use purely quarterly data and, amongst the former, factor models perform best.Bridge models, Dynamic factor models, real-time data flow model

    Short-term forecasting of GDP using large monthly datasets: a pseudo real-time forecast evaluation exercise.

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    This paper evaluates different models for the short-term forecasting of real GDP growth in ten selected European countries and the euro area as a whole. Purely quarterly models are compared with models designed to exploit early releases of monthly indicators for the nowcast and forecast of quarterly GDP growth. Amongst the latter, we consider small bridge equations and forecast equations in which the bridging between monthly and quarterly data is achieved through a regression on factors extracted from large monthly datasets. The forecasting exercise is performed in a simulated real-time context, which takes account of publication lags in the individual series. In general, we find that models that exploit monthly information outperform models that use purely quarterly data and, amongst the former, factor models perform best.Bridge models ; Dynamic factor models ; real-time data flow.

    Magnetization of ballistic quantum dots induced by a linear-polarized microwave field

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    On a basis of extensive analytical and numerical studies we show that a linear-polarized microwave field creates a stationary magnetization in mesoscopic ballistic quantum dots with two-dimensional electron gas being at a thermal equilibrium. The magnetization is proportional to a number of electrons in a dot and to a microwave power. Microwave fields of moderate strength create in a one dot of few micron size a magnetization which is by few orders of magnitude larger than a magnetization produced by persistent currents. The effect is weakly dependent on temperature and can be observed with existing experimental techniques. The parallels between this effect and ratchets in asymmetric nanostructures are also discussed.Comment: 10 pages, 11 figs, research at http://www.quantware.ups-tlse.f
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