A new double laser pulse pumping scheme for transient collisionally excited plasma soft X-ray lasers

Within this thesis a new double laser pulse pumping scheme for plasma-based, transient collisionally excited soft x-ray lasers (SXRL) was developed, characterized and utilized for applications. SXRL operations from ~50 up to ~200 electron volt were demonstrated applying this concept. As a central technical tool, a special Mach-Zehnder interferometer in the chirped pulse amplification (CPA) laser front-end was developed for the generation of fully controllable double-pulses to optimally pump SXRLs.rnThis Mach-Zehnder device is fully controllable and enables the creation of two CPA pulses of different pulse duration and variable energy balance with an adjustable time delay. Besides the SXRL pumping, the double-pulse configuration was applied to determine the B-integral in the CPA laser system by amplifying short pulse replica in the system, followed by an analysis in the time domain. The measurement of B-integral values in the 0.1 to 1.5 radian range, only limited by the reachable laser parameters, proved to be a promising tool to characterize nonlinear effects in the CPA laser systems.rnContributing to the issue of SXRL pumping, the double-pulse was configured to optimally produce the gain medium of the SXRL amplification. The focusing geometry of the two collinear pulses under the same grazing incidence angle on the target, significantly improved the generation of the active plasma medium. On one hand the effect was induced by the intrinsically guaranteed exact overlap of the two pulses on the target, and on the other hand by the grazing incidence pre-pulse plasma generation, which allows for a SXRL operation at higher electron densities, enabling higher gain in longer wavelength SXRLs and higher efficiency at shorter wavelength SXRLs. The observation of gain enhancement was confirmed by plasma hydrodynamic simulations.rnThe first introduction of double short-pulse single-beam grazing incidence pumping for SXRL pumping below 20 nanometer at the laser facility PHELIX in Darmstadt (Germany), resulted in a reliable operation of a nickel-like palladium SXRL at 14.7 nanometer with a pump energy threshold strongly reduced to less than 500 millijoule. With the adaptation of the concept, namely double-pulse single-beam grazing incidence pumping (DGRIP) and the transfer of this technology to the laser facility LASERIX in Palaiseau (France), improved efficiency and stability of table-top high-repetition soft x-ray lasers in the wavelength region below 20 nanometer was demonstrated. With a total pump laser energy below 1 joule the target, 2 mircojoule of nickel-like molybdenum soft x-ray laser emission at 18.9 nanometer was obtained at 10 hertz repetition rate, proving the attractiveness for high average power operation. An easy and rapid alignment procedure fulfilled the requirements for a sophisticated installation, and the highly stable output satisfied the need for a reliable strong SXRL source. The qualities of the DGRIP scheme were confirmed in an irradiation operation on user samples with over 50.000 shots corresponding to a deposited energy of ~ 50 millijoule.rnThe generation of double-pulses with high energies up to ~120 joule enabled the transfer to shorter wavelength SXRL operation at the laser facility PHELIX. The application of DGRIP proved to be a simple and efficient method for the generation of soft x-ray lasers below 10 nanometer. Nickel-like samarium soft x-ray lasing at 7.3 nanometer was achieved at a low total pump energy threshold of 36 joule, which confirmed the suitability of the applied pumping scheme. A reliable and stable SXRL operation was demonstrated, due to the single-beam pumping geometry despite the large optical apertures. The soft x-ray lasing of nickel-like samarium was an important milestone for the feasibility of applying the pumping scheme also for higher pumping pulse energies, which are necessary to obtain soft x-ray laser wavelengths in the water window. The reduction of the total pump energy below 40 joule for 7.3 nanometer short wavelength lasing now fulfilled the requirement for the installation at the high-repetition rate operation laser facility LASERIX.rn

Wachstum und Transporteigenschaften dünner Co-basierter Heusler-Filme

For the advancement of spinelectronicsmuch importance is attached to Heusler compounds. Especially compounds with the stoichiometry Co2YZ are supposed to exhibit a large asymmetry between majority and minority electrons at the Fermi edge. Ideally, only majority states are present. This property leads to high magnetoresistive effects. However, the experimental results available at present fall behind the expectations. In particular, a strong reduction of the spin asymmetry with increasing temperature is problematic. For this reason,rnthe investigation of further representatives of this material class as well as optimization of their deposition is required. Therefore, during the course of this work thin Heusler films with the composition Co2Cr0.6Fe0.4Al and Co2Mn1−xFexSi were fabricated. At first, this was accomplished by sputter deposition, which is the standard technique for the preparation of thin Heuslerrnfilms. It resulted also here in samples with high structural order. On the other hand, these films exhibit only a reduced magnetic moment. To improve this situation, a laser ablation system was constructed. The resulting film deposition under ultra-high vacuum led to a clear improvement especially of the magnetic properties. In addition to the improved deposition conditions, this method allowed the flexible variation of the film stoichiometry as well. This possibility was successfully demonstrated in this work by deposition of epitaxial Co2Mn1−xFexSi films. The availableness of these high quality quaternary alloys allowed the systematic investigation of their electronic properties. Band structure calculations predict that the substitution of Mn by Fe lead to a shift of the Fermi energy over the minority energy gap, whereas the density of states remains nearly unchanged. This prediction could by tested by electronic transport measurements. Especially the normal Hall effect, which was measured at these samples, shows a transition from a hole-like charge transport in Co2MnSi to an electron-like transport in Co2FeSi. This is in accordance with corresponding band structure calculations as well as with comparative XMCD experiments. Furthermore, the behavior of the anomalous Hall effect was studied. Here it could be seen, that the effect is influenced by two mechanisms: On the one hand an intrinsic contribution, caused by the topology of the Fermi surface and on the other hand by temperature dependent impurity scattering. These two effects have an opposing influence on the anomalous Hall effect. This can lead to a sign reversal of the anomalous contribution. This behavior has been predicted just recently and was here systematically investigated for the first time for Heusler compounds.

Bottle microresonators for applications in quantum optics and all-optical signal processing

This thesis reports on the experimental realization, characterization and application of a novel microresonator design. The so-called “bottle microresonator” sustains whispering-gallery modes in which light fields are confined near the surface of the micron-sized silica structure by continuous total internal reflection. While whispering-gallery mode resonators in general exhibit outstanding properties in terms of both temporal and spatial confinement of light fields, their monolithic design makes tuning of their resonance frequency difficult. This impedes their use, e.g., in cavity quantum electrodynamics (CQED) experiments, which investigate the interaction of single quantum mechanical emitters of predetermined resonance frequency with a cavity mode. In contrast, the highly prolate shape of the bottle microresonators gives rise to a customizable mode structure, enabling full tunability. The thesis is organized as follows: In chapter I, I give a brief overview of different types of optical microresonators. Important quantities, such as the quality factor Q and the mode volume V, which characterize the temporal and spatial confinement of the light field are introduced. In chapter II, a wave equation calculation of the modes of a bottle microresonator is presented. The intensity distribution of different bottle modes is derived and their mode volume is calculated. A brief description of light propagation in ultra-thin optical fibers, which are used to couple light into and out of bottle modes, is given as well. The chapter concludes with a presentation of the fabrication techniques of both structures. Chapter III presents experimental results on highly efficient, nearly lossless coupling of light into bottle modes as well as their spatial and spectral characterization. Ultra-high intrinsic quality factors exceeding 360 million as well as full tunability are demonstrated. In chapter IV, the bottle microresonator in add-drop configuration, i.e., with two ultra-thin fibers coupled to one bottle mode, is discussed. The highly efficient, nearly lossless coupling characteristics of each fiber combined with the resonator's high intrinsic quality factor, enable resonant power transfers between both fibers with efficiencies exceeding 90%. Moreover, the favorable ratio of absorption and the nonlinear refractive index of silica yields optical Kerr bistability at record low powers on the order of 50 µW. Combined with the add-drop configuration, this allows one to route optical signals between the outputs of both ultra-thin fibers, simply by varying the input power, thereby enabling applications in all-optical signal processing. Finally, in chapter V, I discuss the potential of the bottle microresonator for CQED experiments with single atoms. Its Q/V-ratio, which determines the ratio of the atom-cavity coupling rate to the dissipative rates of the subsystems, aligns with the values obtained for state-of-the-art CQED microresonators. In combination with its full tunability and the possibility of highly efficient light transfer to and from the bottle mode, this makes the bottle microresonator a unique tool for quantum optics applications.

Tailoring molecule nanostructures on insulating surfaces investigated by non-contact atomic force microscopy

Self-assembled molecular structures were investigated on insulating substrate surfaces using non-contact atomic force microscopy. Both, substrate preparation and molecule deposition, took place under ultra-high vacuum conditions. First, C60 molecules were investigated on the TiO2 (110) surface. This surface exhibits parallel running troughs at the nanometer scale, which strongly steer the assembly of the molecules. This is in contrast to the second investigated surface. The CaF2 (111) surface is atomically flat and the molecular assemblyrnwas observed to be far less affected by the surface. Basically different island structures were observed to what is typically know. Based on extensive experimental studies and theoretical considerations, a comprehensive picture of the processes responsible for the island formation of C60 molecules on this insulating surfaces was developed. The key process for the emergence of the observed novel island structures was made out to be the dewetting of molecules from the substrate. This new knowledge allows to further understand andrnexploit self-assembly techniques in structure fabrication on insulating substrate surfaces. To alter island formation and island structure, C60 molecules were codeposited with second molecule species (PTCDI and SubPc) on the CaF2 (111) surface. Depending on the order of deposition, quiet different structures were observed to arise. Thus, these are the first steps towards more complex functional arrangements consisting of two molecule species on insulating surfaces.

A novel functional renormalization group framework for gauge theories and gravity

In this thesis we develop further the functional renormalization group (RG) approach to quantum field theory (QFT) based on the effective average action (EAA) and on the exact flow equation that it satisfies. The EAA is a generalization of the standard effective action that interpolates smoothly between the bare action for krightarrowinfty and the standard effective action rnfor krightarrow0. In this way, the problem of performing the functional integral is converted into the problem of integrating the exact flow of the EAA from the UV to the IR. The EAA formalism deals naturally with several different aspects of a QFT. One aspect is related to the discovery of non-Gaussian fixed points of the RG flow that can be used to construct continuum limits. In particular, the EAA framework is a useful setting to search for Asymptotically Safe theories, i.e. theories valid up to arbitrarily high energies. A second aspect in which the EAA reveals its usefulness are non-perturbative calculations. In fact, the exact flow that it satisfies is a valuable starting point for devising new approximation schemes. In the first part of this thesis we review and extend the formalism, in particular we derive the exact RG flow equation for the EAA and the related hierarchy of coupled flow equations for the proper-vertices. We show how standard perturbation theory emerges as a particular way to iteratively solve the flow equation, if the starting point is the bare action. Next, we explore both technical and conceptual issues by means of three different applications of the formalism, to QED, to general non-linear sigma models (NLsigmaM) and to matter fields on curved spacetimes. In the main part of this thesis we construct the EAA for non-abelian gauge theories and for quantum Einstein gravity (QEG), using the background field method to implement the coarse-graining procedure in a gauge invariant way. We propose a new truncation scheme where the EAA is expanded in powers of the curvature or field strength. Crucial to the practical use of this expansion is the development of new techniques to manage functional traces such as the algorithm proposed in this thesis. This allows to project the flow of all terms in the EAA which are analytic in the fields. As an application we show how the low energy effective action for quantum gravity emerges as the result of integrating the RG flow. In any treatment of theories with local symmetries that introduces a reference scale, the question of preserving gauge invariance along the flow emerges as predominant. In the EAA framework this problem is dealt with the use of the background field formalism. This comes at the cost of enlarging the theory space where the EAA lives to the space of functionals of both fluctuation and background fields. In this thesis, we study how the identities dictated by the symmetries are modified by the introduction of the cutoff and we study so called bimetric truncations of the EAA that contain both fluctuation and background couplings. In particular, we confirm the existence of a non-Gaussian fixed point for QEG, that is at the heart of the Asymptotic Safety scenario in quantum gravity; in the enlarged bimetric theory space where the running of the cosmological constant and of Newton's constant is influenced by fluctuation couplings.

Messa a punto e validazione di metodiche analitiche per la determinazione di micotossine in matrici biologiche mediante UPLC-MS/MS

La presenza di micotossine nelle materie prime desta grande preoccupazione a causa delle importanti implicazioni nella sicurezza di alimenti e mangimi. Lo scopo di questo lavoro è stato quello di mettere a punto e validare una metodica analitica rapida e semplice, in cromatografia liquida ad ultra prestazione accoppiata a spettrometria di massa-tandem (UPLC-MS/MS), per la determinazione simultanea di differenti micotossine: aflatossine (B1, B2, G1, G2), ocratossina A, fumonisine (B1, B2), deossinivalenolo e zearalenone in matrici biologiche. Il metodo sviluppato per l’analisi di campioni di mangime secco per cani ha mostrato prestazioni adeguate ed è stato applicato a 49 campioni reperibili in commercio, al fine di valutare la sua efficacia e di ottenere alcuni dati preliminari sulla contaminazione da micotossine in alimenti per cani disponibili sul mercato italiano. Lo studio ha evidenziato una percentuale alta di campioni positivi, contenenti principalmente fumonisine, deossinivalenolo e ocratossina A; tutti i tenori si sono dimostrati inferiori al limite di legge previsto (Racc. CE 576/2006). Una seconda metodica è stata messa a punto e validata per l’identificazione e la quantificazione micotossine in campioni di formaggio; per questa matrice è stata inserita anche l’aflatossina M1, specifica dei prodotti lattiero - caseari. Le differenti proprietà chimico-fisiche degli analiti e la complessità della matrice hanno implicato alcune difficoltà nello sviluppo della metodica. Tuttavia, il metodo validato si è mostrato rapido, semplice ed affidabile ed è stato applicato a diversi tipi di formaggi per verificarne la versatilità. I risultati preliminari hanno mostrato l’assenza di contaminazione da parte delle micotossine in oggetto. Entrambi i metodi si sono dimostrati utili per il monitoraggio di contaminanti in matrici complesse ad oggi ancora poco studiate.

The calcite(10-14) surface: a versatile substrate for molecular self-assembly

This thesis presents a detailed and successful study of molecular self-assembly on the calcite CaCO3(10-14) surface. One reason for the superior applicability of this particular surface is given by reflecting the well-known growth modes. Layer-by-layer growth, which is a necessity for the formation of templated two-dimensional (2D) molecular structures, is particularly favoured on substrates with a high surface energy. The CaCO3(10-14) surface is among those substrates and, thus, most promising. rnrnAll experiments in this thesis were performed using the non-contact atomic force microscope (NC-AFM) under ultra-high vacuum conditions. The acquisition of drift-free data became in this thesis possible owing to the herein newly developed atom-tracking system. This system features a lateral tip-positioning precision of at least 50pm. Furthermore, a newly developed scan protocol was implemented in this system, which allows for the acquisition of dense three-dimensional (3D) data under room-temperature conditions. An entire 3D data set from a CaCO3(10-14) surface consisting of 85x85x500 pixel is discussed. rnrnThe row-pairing and (2x1) reconstructions of the CaCO3(10-14) surface constitute most interesting research subjects. For both reconstructions, the NC-AFM imaging was classified to a total of 12 contrast modes. Eight of these modes were observed within this thesis, some of them for the first time. Together with literature findings, a total of 10 modes has been observed experimentally to this day. Some contrast modes presented themselves as highly distance-dependent and at least for one contrast mode, a severe tip-termination influence was found. rnrnMost interestingly, the row-pairing reconstruction was found to break a symmetry element of the CaCO3(10-14) surface. With the presence of this reconstruction, the calcite (10-14) surface becomes chiral. From high-resolution NC-AFM data, the identification of the enantiomers is here possible and is presented for one enantiomer in this thesis. rnrnFive studies of self-assembled molecular structures on calcite (10-14) surfaces are presented. Only for one system, namely HBC/CaCO3(10-14), the formation of a molecular bulk structure was observed. This well-known occurence of weak molecule-insulator interaction hinders the investigation of two-dimensional molecular self-assembly. It was, however, possible to force the formation of an island phase for this system upon following a variable-temperature preparation. rnFor the C60/CaCO3(10-14) system it is most notably that no branched island morphologies were found. Instead, the first C60 layer appeared to wet the calcite surface. rnrnIn all studies, the molecules arranged themselves in ordered superstructures. A templating effect due to the underlying calcite substrate was evident for all systems. This templating strikingly led either to the formation of large commensurate superstructures, such as (2x15) with a 14 molecule basis for the C60/CaCO3(10-14) system, or prevented the vast growth of incommensurate molecular motifs, such as the chicken-wire structure in the trimesic acid (TMA)/CaCO3(10-14) system. rnrnThe molecule-molecule and the molecule-substrate interaction was increased upon choosing molecules with carboxylic acid moieties in the third, fourth and fifth study, using terephthalic acid, TMA and helicene molecules. In all these experiments, hydrogen-bonded assemblies were created. rnrnDirected hydrogen bond formation combined with intermolecular pi-pi interaction is employed in the fifth study, where the formation of uni-directional molecular "wires" from single helicene molecules succeeded. Each "wire" is composed of heterochiral helicene pairs, well-aligned along the [01-10] substrate direction and stabilised by pi-pi interaction.

Strahlungsinduzierte Mukositis als Risiko der Raumfahrt : Modelluntersuchungen an Röntgen- und Schwerionen-bestrahlten organotypischen Mundschleimhaut-Modellen

Während ausgedehnter Weltraumflüge zum Mond und Mars wäre die Besatzung eines Raumschiffs dicht ionisierender Schwerionenstrahlung, der sogenannten kosmischen Strahlung, ausgesetzt. Da bei vielen Krebspatienten die orale Mukositis als eine gravierende Nebenwirkung bei der herkömmlichen Strahlentherapie auftritt, könnte diese Erkrankung ein medizinisches Problem während ausgedehnter Weltraumflüge darstellen. Allerdings liegen bislang keine Untersuchungen über eine mögliche Mukositis-induzierte Wirkung von Schwerionenstrahlung vor. Um das Risiko strahlungsinduzierter oraler Mukositis durch kosmische Strahlung abzuschätzen, wurden dreidimensionale organotypische Mundschleimhaut-Modelle 12C Schwerionen- bzw. Röntgenstrahlung ausgesetzt und nach definierten Inkubationszeiten kryokonserviert. Aus dem Material wurden Kryoschnitte gefertigt, mit denen anschließend histologische und immunhistologische Fluoreszenzfärbungen zum Nachweis von zum Beispiel Kompaktheitsverlust, Doppelstrangbrüchen der DNA und NF-κB-Aktivierung durchgeführt wurden. Die Ausschüttung von Tumornekrosefaktor α, Interleukin 1β, Interleukin 6 und Interleukin 8 wurde in Probenüberständen mittels ELISA analysiert. Das Hauptaugenmerk dieser Studie lag dabei auf den frühen durch Strahlung verursachten Effekten. rnIm Rahmen dieser Dissertation wurde ein dreidimensionales Mundschleimhaut-Modell etabliert, das verglichen mit humaner Mundschleimhaut viele organotypische Differenzierungsmarker und in vivo-ähnliche Reaktionen auf bestimmte Reize zeigte. Nach einer Bestrahlung mit schweren Kohlenstoffionen bzw. mit Röntgenstrahlung wurden strahlungsinduzierte Effekte auf mehreren Ebenen detektiert. Bereits 1 h nach Bestrahlung konnten dosisabhängig vermehrte Doppelstrangbrüche in der DNA detektiert werden, wobei bei gleicher Dosis Schwerionenstrahlung im Durchschnitt doppelt so viele DSB verursachte wie Röntgenstrahlung. Das Mundschleimhaut-Modell reagierte auf beide Strahlungsarten mit einer Aktivierung des Transkriptionsfaktors NF-κB p50, wobei Röntgenstrahlung diese Aktivierung früher induzierte als Schwerionen. Eine strahlungsinduzierte Aktivierung von NF-κB p65 wurde in den organotypischen Kulturen zu den untersuchten Zeitpunkten nicht beobachtet. Im Vergleich zu nicht bestrahlten Kulturen waren die Konzentrationen von Interleukin 6 und Interleukin 8 unabhängig von der Strahlungsqualität nach Bestrahlung signifikant erhöht. Interleukin-1β dagegen wurde nur nach Röntgenbestrahlung signifikant vermehrt ausgeschüttet. In Schwerionen-bestrahlten Proben wurden zwar tendenziell höhere Konzentrationen beobachtet, statistische Signifikanzen ergaben sich aber nicht. Die Analysen zur TNF-α- und IFN-γ-Ausschüttung in bestrahlten organotypischen Kulturen ergaben innerhalb des gewählten Beobachtungszeitraums von 48 h keine strahlungsinduzierten Effekte. Bei den Untersuchungen der Proliferation in den Zellen der bestrahlten organotypischen Kulturen wurde bereits 24 h nach Röntgenstrahlung und 3 Tage nach Schwerionenstrahlung eine deutliche verminderte Proliferation beobachtet. Des Weiteren zeigte das Mundschleimhaut-Modell unabhängig von Strahlungsqualitäten einen eindeutigen Verlust in der Zellintegrität und daraus resultierenden Kompaktheitsverlust des Gewebes, was in der in vivo-Situation wahrscheinlich einer Gewebedegeneration entspricht. rnNach Bestrahlung mit sowohl Röntgenstrahlung als auch schweren Ionen wurden im gewählten Mukosa-Modell innerhalb von 48 h nach Behandlung strahlungsinduzierte proinflammatorische Marker eindeutig und reproduzierbar detektiert. Dies deutet darauf hin, dass während langer extraterrestrischer Expeditionen das Risiko der oralen Mukositis einkalkuliert und mit den daraus folgenden Konsequenzen gerechnet werden muss.rn

Stabilizing molecular self-assemblies via on-surface reactions

Für die Realisierung zukünftiger Technologien, wie z.B. molekulare Elektronik, werden Strategien benötigt, um funktionale Strukturen direkt auf Oberflächen zu erzeugen. Für die Bewältigung dieser Aufgabe ist die molekulare Selbstanordnung ein äußerst vielversprechender Bottom-up-Ansatz. Hierbei ist eine der größten Herausforderungen das Zusammenspiel aus intramolekularer Wechselwirkung und der Wechselwirkung zwischen Substrat und Molekülen in ein Gleichgewicht zu bringen. Da jedoch die wirkenden Kräfte der molekularen Selbstanordnung ausschließlich reversibler Natur sind, ist eine langfristige Stabilität fragwürdig. Somit ist die kovalente Verknüpfung der gebildeten Strukturen durch Reaktionen direkt auf der Oberfläche unerlässlich, um die Stabilität der Strukturen weiter zu erhöhen. Hierzu stellt die vorliegende Arbeit eine ausführliche Studie zu molekularer Selbstanordnung und der zielgerichteten Modifikation ebensolcher Strukturen dar. Durch den Einsatz von hochauflösender Rasterkraftmikroskopie im Ultrahochvakuum, welche es erlaubt einzelne Moleküle auf Nichtleitern abzubilden, wurde der maßgebliche Einfluss von Ankerfunktionalitäten auf den Prozess der molekularen Selbstanordnung gezeigt. Des Weiteren konnte die Stabilität der selbst angeordneten Strukturen durch neue Oberflächenreaktionskonzepte entschieden verbessert werden. Der Einfluss von Ankerfunktionen, die elektrostatische Wechselwirkung zwischen Molekül und Substrat vermitteln, auf den Strukturbildungsprozess der molekularen Selbstanordnung wird eingehend durch den Vergleich eines aromatischen Moleküls und seines vierfach chlorierten Derivates gezeigt. Für diese beiden Moleküle wurde ein deutlich unterschiedliches Verhalten der Selbstanordnung beobachtet. Es wird gezeigt, dass die Fähigkeit zur Bildung selbst angeordneter, stabiler Inseln entscheidend durch die Substituenten und die Abmessungen des Moleküls beeinflusst wird. Auch wird in dieser Arbeit die erste photochemische Reaktion organischer Moleküle auf einem Isolator gezeigt. Qualitative und quantitative Ergebnisse liefern ein detailliertes Bild darüber, wie die Abmessungen des Substratgitters die Richtung der Reaktion gezielt beeinflussen. Des Weiteren wird ein allgemeines Konzept zur selektiven Stabilisierung selbstangeordneter Molekülstrukturen durch den kontrollierten Transfer von Elektronen präsentiert. Durch die gezielte Steuerung der Menge an Dotierungsatomen wird die Desorptionstemperatur der molekularen Inseln signifikant erhöht und das Desorptionsverhalten der Inseln entschieden verändert. Diese Arbeit präsentiert somit erfolgreich durchgeführte Strategien um den Prozess der molekularen Selbstanordnung zu steuern, sowie entscheidende Mechanismen um die Stabilisierung und Modifizierung von selbst angeordneten Strukturen zu gewährleisten.

Correlazioni tra UHECRs di Auger e neutrini di ANTARES

Questo lavoro ha lo scopo di individuare una strada nella ricerca di un confronto tra canditati eventi di neutrino cosmico da parte dell'esperimento ANTARES ,nel Mar Mediterraneo a sud est della costa di Tolone, in Francia e gli Ultra High Energy Cosmic Rays dell'osservatorio Pierre Auger in Argentina. Si utilizzano dati raccolti dal telescopio di neutrini ANTARES tra il 2007 e il 2013, con energie dell'ordine del TeV, e quelli di Auger ottenuti tra il 2004 e il 2014, con energie dei raggi cosmici dell'ordine dell'EeV. Entrambi gli apparati sono basati sulla rivelazione di radiazione Cherenkov, ma l'osservatorio di Auger è dotato di un secondo rivelatore di luminescenza che lavora in sincrono per ridurre gli errori sistematici associati ai singoli rivelatori. Le distribuzioni degli eventi in base alle direzioni di arrivo e dell' energia osservata, sono i parametri necessari per la ricerca di una correlazione. Dalla sovrapposizione delle distribuzioni possiamo evidenziare le zone di visibilità caratteristiche di ciascun esperimento, e condurre un eventuale successiva analisi finalizzata ad una identificazione univoca di eventi coincidenti.

What percentage of people in the general population satisfies the current clinical at-risk criteria of psychosis?

The clinical validity of at-risk criteria of psychosis had been questioned based on epidemiological studies that have reported much higher prevalence and annual incidence rates of psychotic-like experiences (PLEs as assessed by either self rating questionnaires or layperson interviews) in the general population than of the clinical phenotype of psychotic disorders (van Os et al., 2009). Thus, it is unclear whether “current at-risk criteria reflect behaviors so common among adolescents and young adults that a valid distinction between ill and non-ill persons is difficult” (Carpenter, 2009). We therefore assessed the 3-month prevalence of at-risk criteria by means of telephone interviews in a randomly drawn general population sample from the at-risk age segment (age 16–35 years) in the Canton Bern, Switzerland. Eighty-five of 102 subjects had valid phone numbers, 21 of these subjects refused (although 6 of them signaled willingness to participate at a later time), 4 could not be contacted. Sixty subjects (71% of the enrollment fraction) participated. Two participants met exclusion criteria (one for being psychotic, one for lack of language skills). Twenty-two at-risk symptoms were assessed for their prevalence and severity within the 3 months prior to the interview by trained clinical raters using (i) the Structured Interview for Prodromal Syndromes (SIPS; Miller et al., 2002) for the evaluation of 5 attenuated psychotic and 3 brief limited intermittent psychotic symptoms (APS, BLIPS) as well as state-trait criteria of the ultra-high-risk (UHR) criteria and (ii) the Schizophrenia Proneness Instrument, Adult version (SPI-A; Schultze-Lutter et al., 2007) for the evaluation of the 14 basic symptoms included in COPER and COGDIS (Schultze-Lutter et al., 2008). Further, psychiatric axis I diagnoses were assessed by means of the Mini-International Neuropsychiatric Interview, M.I.N.I. (Sheehan et al., 1998), and psychosocial functioning by the Scale of Occupational and Functional Assessment (SOFAS; APA, 1994). All interviewees felt ‘rather’ or ‘very’ comfortable with the interview. Of the 58 included subjects, only 1 (2%) fulfilled APS criteria by reporting the attenuated, non-delusional idea of his mind being literally read by others at a frequency of 2–3 times a week that had newly occurred 6 weeks ago. BLIPS, COPER, COGDIS or state-trait UHR criteria were not reported. Yet, twelve subjects (21%) described sub-threshold at-risk symptoms: 7 (12%) reported APS relevant symptoms but did not meet time/frequency criteria of APS, and 9 (16%) reported COPER and/or COGDIS relevant basic symptoms but at an insufficient frequency or as a trait lacking increase in severity; 4 of these 12 subjects reported both sub-threshold APS and sub-threshold basic symptoms. Table 1 displays type and frequency of the sub-threshold at-risk symptoms.

Früherkennung von Psychosen bei Kindern und Adoleszenten - Sind entwicklungsbezogene Besonderheiten ausreichend berücksichtigt

The early detection and treatment of persons at risk for psychosis is currently regarded as a promising strategy in fighting the devastating consequences of psychotic disorders. The two current favored at-risk approaches, i.e., the «ultra high risk» and the «basic symptom» criteria, were developed mainly using adult samples. Initial evidence suggests, however, that they cannot simply be applied to children and adolescents. For «ultra-high risk» criteria, there is indication of some attenuated psychotic symptoms being potentially nonspecific in adolescents, and of brief limited intermittent symptoms being difficult to clinically classify in children when observable behavioral correlates are missing. For basic symptoms, too, only a preliminary indication of their usefulness in children and adolescents exists. Since developmental peculiarities in the assessment of basic symptoms should be considered, a child and youth version of the Schizophrenia Proneness Instrument (SPI-CY) was developed. In conclusion, research on the clinical-prognostic validity of the at-risk criteria and their potential adaption to the special needs of children and adolescents is needed. If a «Prodromal Risk Syndrome for Psychosis» or «Attenuated Psychotic Symptoms Syndrome» are included in the upcoming DSM-5, it should be highlighted that its suitability for children and adolescents is only insufficiently known.

Instrumento de Propensão à Esquizofrenia - Versão Adulto (SPI-A)

O Instrumento de Propensão a Esquizofrenia tem suas origens no conceito de sintoma básico descrito primeiramente por Gerd Huber. Sintomas básicos são distúrbios sub-clínicos sutis auto-experimentados da motivação, da tolerância ao estresse, do afeto, do pensamento, do discurso, da ação motora e da percepção, os quais são claramente distintos fenomenologicamente dos sintomas psicóticos. Eles podem estar presentes antes do primeiro episódio psicótico, entre e após episódios psicóticos, e mesmo durante os próprios episódios psicóticos. Pensava-se que eles eram a mais imediata expressão psicopatológica da alteração somática por trás do desenvolvimento da psicose – assim o termo “básico”. Sintomas básicos são fenomenologicamente diferentes dos estados mentais conhecidos pelo paciente/sujeito do que ele/ela considera seu eu “normal” e assim são claramente distinguíveis dos distúrbios sutis descritos como traços naqueles com alto risco genético. Além disso, sintomas básicos são claramente distintos fenomenologicamente dos sintomas psicóticos atenuados ou francos - empregados no critério de “risco-ultra-alto” (Ultra High Risk − UHR) para risco iminente de um primeiro episódio psicótico – já que não são necessariamente observáveis por outros, como pensamento e discurso estranhos, sintomas negativos e alteração formal do pensamento. Eles são considerados como sendo desenvolvidos no próprio sujeito, contrariamente aos distúrbios de percepção esquizotípicos e alucinações, e não afetam primariamente o conteúdo do pensamento como o fazem o pensamento mágico, as idéias de referência, a ideação paranóide e os delírios.

Second-Generation Orthopaedic Measurement Device for in-vivo Assessment of Bone Quality

There are two main types of bone in the human body, trabecular and cortical bone. Cortical bone is primarily found on the outer surface of most bones in the body while trabecular bone is found in vertebrae and at the end of long bones (Ross 2007). Osteoporosis is a condition that compromises the structural integrity of trabecular bone, greatly reducing the ability of the bone to absorb energy from falls. The current method for diagnosing osteoporosis and predicting fracture risk is measurement of bone mineral density. Limitations of this method include dependence on the bone density measurement device and dependence on type of test and measurement location (Rubin 2005). Each year there are approximately 250,000 hip fractures in the United States due to osteoporosis (Kleerekoper 2006). Currently, the most common method for repairing a hip fracture is a hip fixation surgery. During surgery, a temporary guide wire is inserted to guide the permanent screw into place and then removed. It is believed that directly measuring this screw pullout force may result in a better assessment of bone quality than current indirect measurement techniques (T. Bowen 2008-2010, pers. comm.). The objective of this project is to design a device that can measure the force required to extract this guide wire. It is believed that this would give the surgeon a direct, quantitative measurement of bone quality at the site of the fixation. A first generation device was designed by a Bucknell Biomedical Engineering Senior Design team during the 2008- 2009 Academic Year. The first step of this project was to examine the device, conduct a thorough design analysis, and brainstorm new concepts. The concept selected uses a translational screw to extract the guide wire. The device was fabricated and underwent validation testing to ensure that the device was functional and met the required engineering specifications. Two tests were conducted, one to test the functionality of the device by testing if the device gave repeatable results, and the other to test the sensitivity of the device to misalignment. Guide wires were extracted from 3 materials, low density polyethylene, ultra high molecular weight polyethylene, and polypropylene and the force of extraction was measured. During testing, it was discovered that the spring in the device did not have a high enough spring constant to reach the high forces necessary for extracting the wires without excessive deflection of the spring. The test procedure was modified slightly so the wires were not fully threaded into the material. The testing results indicate that there is significant variation in the screw pullout force, up to 30% of the average value. This significant variation was attributed to problems in the testing and data collection, and a revised set of tests was proposed to better evaluate the performance of the device. The fabricated device is a fully-functioning prototype and further refinements and testing of the device may lead to a 3rd generation version capable of measuring the screw pullout force during hip fixation surgery.

The Schizophrenia Proneness Instrument, Child and Youth version (SPI-CY): Practicability and discriminative validity

Background Basic symptom (BS) criteria have been suggested to complement ultra-high risk (UHR) criteria in the early detection of psychosis in adults and in children and adolescents. To account for potential developmental particularities and a different clustering of BS in children and adolescents, the Schizophrenia Proneness Instrument, Child and Youth version (SPI-CY) was developed. Aims The SPI-CY was evaluated for its practicability and discriminative validity. Method The SPI-CY was administered to 3 groups of children and adolescents (mean age 16; range=8–18; 61% male): 23 at-risk patients meeting UHR and/or BS criteria (AtRisk), 22 clinical controls (CC), and 19 children and adolescents from the general population (GPS) matched to AtRisk in age, gender, and education. We expected AtRisk to score highest on the SPI-CY, and GPS lowest. Results The groups differed significantly on all 4 SPI-CY subscales. Pairwise post-hoc comparisons confirmed our expectations for all subscales and, at least on a descriptive level, most items. Pairwise subscale differences indicated at least moderate group effects (r≥0.37) which were largest for Adynamia (0.52≤r≥0.70). Adynamia also performed excellent to outstanding in ROC analyses (0.813≤AUC≥0.981). Conclusion The SPI-CY could be a helpful tool for detecting and assessing BS in the psychosis spectrum in children and adolescents, by whom it was well received. Furthermore, its subscales possess good discriminative validity. However, these results require validation in a larger sample, and the psychosis-predictive ability of the subscales in different age groups, especially the role of Adynamia, will have to be explored in longitudinal studies.