Photoproduktion neutraler Pionen am Proton mit linear polarisierten Photonen im Bereich der Delta(1232)-Resonanz

Hinweise auf die innere Struktur des Nukleons, dessenbeobachtbares Quadrupolmoment verschwindet, lassen sich u.a.durch die Untersuchung des N->Delta(1232)-Übergangsgewinnen. Dieser wird von der magnetischen Dipolanregung M1- einem Spinflip-Übergang - dominiert. In der Reaktion (gamma(lin. pol.) p -> p pi0) gelingt es mittels der Photonasymmetrie Sigma, das Signal der kleinen elektrischen Quadrupolamplitude E2 in einem Interferenztermmit der M1-Amplitude zu verstärken und das VerhältnisREM=E2/M1 des betrachteten Übergangs zu bestimmen. DieE2-Amplitude des N->Delta-Übergangs läßt auf eineDeformation des Nukleons und/oder der Delta-Resonanzschließen. Das zugehörige Experiment wurde am MainzerElektronenbeschleuniger MAMI durchgeführt. Durch kohärenteBremsstrahlung der Elektronen an einem Diamantradiatorstanden im Bereich der Delta(1232)-Resonanz linear polarisierte Photonen zur Verfügung. Insgesamt wurden reellePhotonen im Bereich Egamma=(200-790) MeV von derA2-Photonenmarkierungsanlage (Glasgow--Tagger)energiemarkiert. Mit dem Photonenspektrometer TAPS wurden die pi0-Mesonen über ihre beiden Zerfallsphotonennachgewiesen. Die gewählte Anordnung der 504BaF2-Einzelkristalle um ein Flüssigwasserstofftargeterlaubte den pi0-Nachweis im vollen Polarwinkelbereich. Die Datenbasis zur pi0-Photoproduktion am Proton konntehinsichtlich der Wirkungsquerschnitte und Photonasymmetriendurch Datenpunkte über den gesamten Polarwinkelbereichhinweg nachdrücklich erweitert werden.Eine weiterführende Multipolanalyse der neuen(Proton-pi0)-Daten ermöglichte im Energiebereich derDelta-Resonanz die Bestimmung der s- und p-WellenIsospinamplituden von E0+, M1-, E1+ und M1+.

Strahlungsbegleitete Pion-Photoproduktion am Proton

Im Jahre 1997 wurden von Tatischeff et al. bei der Reaktion p p -> X p pi+ resonanzartige Zustände im Spektrum der invarianten Masse des fehlenden Nukleons X bei M = 1004, 1044 und 1094 MeV gefunden. In einem zweiten Experiment von Filkov et al. beobachtete man bei der Reaktion p d -> p p X Resonanzstrukturen bei M = 966, 986 und 1003 MeV. Solche exotischen Resonanzen widersprechen etablierten Nukleonenmodellen, die die Delta(1232)-Resonanz als ersten Anregungszustand beschreiben. Zur Deutung der beobachteten Strukturen wurden Quarkcluster-Modelle mit und ohne Farb-Magnet-Wechselwirkungen entwickelt. Lvov et al. zweifelten die experimentellen Ergebnisse an, da keine Strukturen in den Daten zur reellen Comptonstreuung gefunden wurden. Als Gegenargument wurde von Kobushkin vorgeschlagen, dass diese Resonanzen eine total-antisymmetrische Spin-Flavour-Wellenfunktion haben und nur der N-2Gamma-Zerfall erlaubt wäre. In dieser Arbeit wurde die Reaktion g p -> X pi+ -> n g g pi+ zur Suche nach diesen exotischen Resonanzen verwendet. Die Daten wurden parallel zur Messung der Pion-Polarisierbarkeiten am Mainzer Beschleuniger MAMI genommen. Durch Bremsstrahlung der Elektronen an einer Radiatorfolie wurden reelle Photonen erzeugt, deren Energie von der A2-Photonenmarkierungsanlage (Glasgow-Tagger) bestimmt wurde. Als Protontarget wurde ein 10 cm langes Flüssigwasserstoff-Target verwendet. Geladene Reaktionsprodukte wurden unter Vorwärtswinkeln Theta < 20 Grad bezüglich der Strahlachse in einer Vieldraht-Proportionalkammer nachgewiesen, während Photonen im Spektrometer TAPS mit 526 BaF2-Kristallen unter Polarwinkeln Theta > 60 Grad detektiert wurden. Zum Nachweis von Neutronen stand ein Flugzeitdetektor mit insgesamt 111 Einzelmodulen zur Verfügung. Zum Test der Analysesoftware und des experimentellen Aufbaus wurden zusätzlich die Reaktionskanäle g p -> p pi0 und g p -> n pi0 pi+ ausgewertet. Für die Ein-Pion-Produktion wurden differentielle Wirkungsquerschnitte unter Rückwärtswinkeln bestimmt und mit theoretischen Modellen und experimentellen Werten verglichen. Für den Kanal g p -> n pi0 pi+ wurden Spektren invarianter Massen für verschiedene Teilchenkombinationen ermittelt und mit einer Simulation verglichen. Die Daten legen nahe, dass die Reaktion hauptsächlich über eine Anregung der Delta0(1232)-Resonanz verläuft. Bei der Suche nach exotischen Resonanzen wurden keine statistisch signifikanten Strukturen gefunden. Es wurden Obergrenzen für den differentiellen Wirkungsquerschnitt ermittelt.

Polymorphs solvates and co-crystals of molecular materials

The scope of my research project is to produce and characterize new crystalline forms of organic compounds, focusing the attention on co-crystals and then transferring these notions on APIs to produce co-crystals of potential interest in the pharmaceutical field. In the first part of this work co-crystallization experiments were performed using as building blocks the family of aliphatic dicarboxylic acids HOOC-(CH2)n-COOH, with n= 2-8. This class of compounds has always been an object of study because it is characterized by an interesting phenomenon of alternation of melting points: the acids with an even number of carbon atoms show a melting point higher than those with an odd one. The acids were co-crystallized with four dipyridyl molecules (formed by two pyridine rings with a different number of bridging carbon atoms) through the formation of intermolecular interactions N•••(H)O. The bases used were: 4,4’-bipyridine (BPY), 1,2-bis(4-pyridyl)ethane (BPA), 1,2-(di-4-pyridyl)ethylene (BPE) and 1,2-bis(4-pyridyl)propane (BPP). The co-crystals obtained by solution synthesis were characterized by different solid-state techniques to determine the structure and to see how the melting points in co-crystals change. In the second part of this study we tried to obtain new crystal forms of compounds of pharmaceutical interest. The APIs studied are: O-desmethylvenlafaxine, Lidocaine, Nalidixic Acid and Sulfadiazine. Each API was subjected to Polymorph Screening and Salt/Co-crystal Screening experiments to identify new crystal forms characterized by different properties. In a typical Salt/Co-crystal Screening the sample was made to react with a co-former (solid or liquid) through different methods: crystallization by solution, grinding, kneading and solid-gas reactions. The new crystal forms obtained were characterized by different solid state techniques (X-ray single crystal diffraction, X-ray powder diffraction, Differential Scanning Calorimetry, Thermogravimetric Analysis, Evolved gas analysis, FT-IR – ATR, Solid State N.M.R).

Study of the helicity dependence of single pion photoproduction on the deuteron

Der erste experimentelle Test der GDH-Summenregel für das Proton wurde 1998 am MAMI-Beschleuniger der Universität Mainz durchgeführt. Ferner wurde ein Pilot-Experiment mit einem polarisierten Deuteron-Target vorgenommen. Dieselbe Kollaboration führte 2003 ein auf das Deuteron ausgerichtetes Experiment durch mit der Absicht, die GDH-Summenregel für das Neutron zu untersuchen. Der in beiden Experimenten verwendete Aufbau erlaubt nicht nur die Messung des totalen Wirkungsquerschnitts, sondern auch gleichzeitig einzelne Teilreaktionen zu studieren. In dieser Arbeit werden die Daten des Deuteron-Pilot-Experiments von 1998 analysiert. Desweiteren wird eine Studie der Helizitätsabhängigkeit der differenziellen Wirkungsquerschnitte für drei Pion-Photoproduktionskanäle des Deuterons in der oberen Hälfte der Delta-Resonanz präsentiert. Diese Ergebnisse werden mit einem theoretischen Modell verglichen. Dabei wurde eine hinreichend gute Übereinstimmung für die unpolarisierten Reaktionen gefunden, während für die polarisierten Kanäle kleinere Diskrepanzen beobachtet wurden. Der Targetpolarisationsgrad ist einer der relevanten Parameter, der für eine absolute Normalisierung der Wirkungsquerschnitte notwendig ist. Die Analyse dieses Parameters für die 2003er Daten wird in der vorliegenden Arbeit vorgestellt. Zur Zeit ist in Mainz ein Frozen-Spin-Target im Bau. Es wird als Target für polarisierte Protonen oder polarisierte Deuteronen für zukünftige Experimente mit dem Crystal Ball zur Verfügung stehen. Die Vorbereitungen der verschiedenen Subsysteme dieses Aufbaus stellten einen wichtigen Teil dieser Arbeit dar. Die fundamentalen Grundlagen der Methode und deren technische Umsetzung, sowie der momentane Status der Aufbauarbeiten am Target werden im Detail präsentiert.

A universal delta model

This thesis presents a universal model of documents and deltas. This model formalize what it means to find differences between documents and to shows a single shared formalization that can be used by any algorithm to describe the differences found between any kind of comparable documents. The main scientific contribution of this thesis is a universal delta model that can be used to represent the changes found by an algorithm. The main part of this model are the formal definition of changes (the pieces of information that records that something has changed), operations (the definitions of the kind of change that happened) and deltas (coherent summaries of what has changed between two documents). The fundamental mechanism tha makes the universal delta model a very expressive tool is the use of encapsulation relations between changes. In the universal delta model, changes are not always simple records of what has changed, they can also be combined into more complex changes that reflects the detection of more meaningful modifications. In addition to the main entities (i.e., changes, operations and deltas), the model describes and defines also documents and the concept of equivalence between documents. As a corollary to the model, there is also an extensible catalog of possible operations that algorithms can detect, used to create a common library of operations, and an UML serialization of the model, useful as a reference when implementing APIs that deal with deltas. The universal delta model presented in this thesis acts as the formal groundwork upon which algorithm can be based and libraries can be implemented. It removes the need to recreate a new delta model and terminology whenever a new algorithm is devised. It also alleviates the problems that toolmakers have when adapting their software to new diff algorithms.

Single meson production in proton diffraction at 190 GeV/c at COMPASS

The quark model successfully describes all ground state bary-ons as members of $SU(N)$ flavour multiplets. For excited baryon states the situation is totally different. There are much less states found in the experiment than predicted in most theoretical calculations. This fact has been known for a long time as the 'missing resonance problem'. In addition, many states found in experiments are only poorly measured up to now. Therefore, further experimental efforts are needed to clarify the situation.rnrnAt mbox{COMPASS}, reactions of a $190uskgigaeVperclight$ hadron beam impinging on a liquid hydrogen target are investigated.rnThe hadron beam contains different species of particles ($pi$, $K$, $p$). To distinguish these particles, two Cherenkov detectors are used. In this thesis, a new method for the identification of particles from the detector information is developed. This method is based on statistical approaches and allows a better kaon identification efficiency with a similar purity compared to the method, which was used before.rnrnThe reaction $pprightarrow ppX$ with $X=(pi^0,~eta,~omega,~phi)$ is used to study different production mechanisms. A previous analysis of $omega$ and $phi$ mesons is extended to pseudoscalar mesons. As the resonance contributions in $peta$ are smaller than in $ppi^0$ a different behaviour of these two final states is expected as a function of kinematic variables. The investigation of these differences allows to study different production mechanisms and to estimate the size of the resonant contribution in the different channels.rnrnIn addition, the channel $pprightarrow ppX$ allows to study baryon resonances in the $pX$ system.rnIn the mbox{COMPASS} energy regime, the reaction is dominated by Pomeron exchange. As a Pomeron carries vacuum quantum numbers, no isospin is transferred between the target proton and the beam proton. Therefore, the $pX$ final state has isospin $textstylefrac{1}{2}$ and all baryon resonances in this channel are $N^ast$ baryons. This offers the opportunity to do spectroscopy without taking $Delta$ resonances into account. rnrnTo disentangle the contributions of different resonances a partial wave analysis (PWA) is used. Different resonances have different spin and parity $J^parity$, which results in different angular distributions of the decay particles. These angular distributions can be calculated from models and then be fitted to the data. From the fit the contributions of the single resonances as well as resonance parameters -- namely the mass and the width -- can be extracted. In this thesis, two different approaches for a partial wave analysis of the reaction $pprightarrow pppi^0$ are developed and tested.

MAGNETO-PHOTONIC CRYSTALS FOR OPTICAL SENSING APPLICATIONS

Among the optical structures investigated for optical sensing purpose, a significant amount of research has been conducted on photonic crystal based sensors. A particular advantage of photonic crystal based sensors is that they show superior sensitivity for ultra-small volume sensing. In this study we investigate polarization changes in response to the changes in the cover index of magneto-optic active photonic band gap structures. One-dimensional photonic-band gap structures fabricated on iron garnet materials yield large polarization rotations at the band gap edges. The enhanced polarization effects serve as an excellent tool for chemical sensing showing high degree of sensitivity for photonic crystal cover refractive index changes. The one dimensional waveguide photonic crystals are fabricated on single-layer bismuth-substituted rare earth iron garnet films ((Bi, Y, Lu)3(Fe, Ga)5O12 ) grown by liquid phase epitaxy on gadolinium gallium garnet substrates. Band gaps have been observed where Bragg scattering conditions links forward-going fundamental waveguide modes to backscattered high-order waveguide modes. Large near-band-edge polarization rotations which increase progressively with backscattered-mode order have been experimentally demonstrated for multiple samples with different composition, film thickness and fabrication parameters. Experimental findings are supported by theoretical analysis of Bloch modes polarization states showing that large near stop-band edge rotations are induced by the magneto-photonic crystal. Theoretical and experimental analysis conducted on polarization rotation sensitivity to waveguide photonic crystal cover refractive index changes shows a monotonic enhancement of the rotation with cover index. The sensor is further developed for selective chemical sensing by employing Polypyrrole as the photonic crystal cover layer. Polypyrrole is one of the extensively studied conducting polymers for selective analyte detection. Successful detection of aqueous ammonia and methanol has been achieved with Polypyrrole deposited magneto-photonic crystals.

T1(Gd) gives comparable information as Delta T1 relaxation rate in dGEMRIC evaluation of cartilage repair tissue

OBJECTIVES: To evaluate the relationship between T1 after intravenous contrast administration (T1Gd) and Delta relaxation rate (DeltaR1) = (1/T1(Gd) - 1/T1o) in the delayed Gadolinium-Enhanced MRI of cartilage (dGEMRIC) evaluation of cartilage repair tissue. MATERIALS AND METHODS: Thirty single MR examinations from 30 patients after matrix-associated autologous chondrocyte transplantations of the knee joint with different postoperative intervals were examined using an 8-channel knee-coil at 3T. T1 mapping using a 3D GRE sequence with a 35/10 degrees flip angle excitation pulse combination was performed before and after contrast administration (dGEMRIC technique). T1 postcontrast (T1(Gd)) and the DeltaR1 (relative index of pre- and postcontrast R1 value) were calculated for repair tissue and the weight-bearing normal appearing control cartilage. For evaluation of the different postoperative intervals, MR exams were subdivided into 3 groups (up to 12 months, 12-24 months, more than 24 months). For statistical analysis Spearman correlation coefficients were calculated. RESULTS: The mean value for T1 postcontrast was 427 +/- 159 ms, for DeltaR1 1.85 +/- 1.0; in reference cartilage 636 +/- 181 ms for T1 postcontrast and 0.83 +/- 0.5 for DeltaR1.The correlation coefficients were highly significant between T1 (Gd) and DeltaR1 for repair tissue (0.969) as well as normal reference cartilage (0.928) in total, and for the reparative cartilage in the early, middle postoperative, and late postoperative interval after surgery (R values: -0.986, -0.970, and -0.978, respectively). Using either T1(Gd) or DeltaR1, the 2 metrics resulted in similar conclusions regarding the time course of change of repair tissue and control tissue, namely that highly significant (P > 0.01) differences between cartilage repair tissue and reference cartilage were found for all follow-up groups. Additionally, for both metrics highly significant differences (P < 0.01) between early follow up and the 2 later postoperative groups for cartilage repair tissue were found. No statistical differences were found between the 2 later follow-up groups of reparative cartilage either for T1 (Gd) or DeltaR1. CONCLUSION: The high correlation between T1 (Gd) and DeltaR1 and the comparable conclusions reached utilizing metric implies that T1 mapping before intravenous administration of MR contrast agent is not necessary for the evaluation of repair tissue. This will help to reduce costs, inconvenience for the patients, simplifies the examination procedure, and makes dGEMRIC more attractive for follow-up of patients after cartilage repair surgeries.

Development and pharmacokinetic characterization of pulmonal and intravenous delta-9-tetrahydrocannabinol (THC) in humans

The aim of the present study was to develop a physiologically compatible inhalation solution of delta-9-tetrahydrocannabinol (THC), and to compare the pharmacokinetic and analgesic properties of pulmonal THC versus pulmonal placebo and intravenous (iv) THC, respectively. Eight healthy volunteers were included in this randomized, double-blind, crossover study. The aqueous THC formulations were prepared by using a solubilization technique. iv THC (0.053 mg/kg body weight), pulmonal THC (0.053 mg/kg), or a placebo inhalation solution was administered as single dose. At defined time points, blood samples were collected, and somatic and psychotropic side effects as well as vital functions monitored. An ice water immersion test was performed to measure analgesia. Using a pressure-driven nebulizer, the pulmonal administration of the THC liquid aerosol resulted in high THC peak plasma levels within minutes. The bioavailability of the pulmonal THC was 28.7 +/- 8.2% (mean +/- SEM). The side effects observed after pulmonal THC were coughing and slight irritation of the upper respiratory tract, very mild psychotropic symptoms, and headache. The side effects after iv THC were much more prominent. Neither pulmonal nor iv THC significantly reduced experimentally induced pain.

Mineralization of calcium phosphate crystals in starch template inducing a brushite kidney stone biomimetic composite

Dicalcium phosphate dihydrate (brushite) and octacalcium phosphate (OCP) crystals are precursors of hydroxyapatite (HAp) for tooth enamel, dentine, and bones formation in living organisms. Here, we introduce a new method for biomimicking brushite and OCP in starch using single and double diffusion techniques. Brushite and OCP crystals were grown by precipitation in starch after gelation. The obtained materials were analyzed by infrared spectroscopy (IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and confocal laser scanning microscopy (CLSM). IR spectra demonstrate starch inclusion by peak shifts in the 2900–3500 cm–1 region. SEM showed two different morphologies: plate-shaped and needle-like crystals. Calcium phosphate/starch aggregates bear strong resemblance to prismatic brushite kidney stones. This may open up a clue to understand the mechanism of kidney stone formation.

40Ar/39Ar single-crystal dating of detrital muscovite and K-feldspar of ODP Holes 116-717A and 116-718C

Detrital K-feldspars and muscovites from Ocean Drilling Program Leg 116 cores that have depositional ages from 0 to 18 Ma have been dated by the 40Ar/39Ar technique. Four to thirteen individual K-feldspars have been dated from seven stratigraphic levels, each of which have a very large range, up to 1660 Ma. At each level investigated, at least one K-feldspar yielded an age minimum which is, within uncertainty, identical to the age of deposition. One to twelve single muscovite crystals from each of six levels have also been studied. The range of muscovite ages is less than that of the K-feldspars and, with one exception, reveal only a 20-Ma spread in ages. As with the K-feldspars, each level investigated contains muscovites with mineral ages essentially identical to depositional ages. These results indicate that a significant portion of the material in the Bengal Fan is first-cycle detritus derived from the Himalayas. Therefore, the significant proportion of sediment deposited in the distal fan in the early to mid Miocene can be ascribed to a significant pulse of uplift and erosion in the collision zone. Moreover, these data indicate that during the entire Neogene, some portion of the Himalayan orogen was experiencing rapid erosion (<= uplift). The lack of granulite facies rocks in the eastern Himalayas and Tibetan Plateau suggests that very rapid uplift must have been distributed in brief pulses in different places in the mountain belt. We suggest that the great majority of the crystals with young apparent ages have been derived from the southern slope of the Himalayas, predominantly from near the main central thrust zone. These data provide further evidence against tectonic models in which the Himalayas and Tibetan plateaus are uplifted either uniformly during the past 40 m.y. or mostly within the last 2 to 5 m.y.

Wet tundra polygon centers and distance between polygon centroids on Samoylov Island, Lena Delta, Siberia, Russia, with links to shape files

Subgrid processes occur in various ecosystems and landscapes but, because of their small scale, they are not represented or poorly parameterized in climate models. These local heterogeneities are often important or even fundamental for energy and carbon balances. This is especially true for northern peatlands and in particular for the polygonal tundra, where methane emissions are strongly influenced by spatial soil heterogeneities. We present a stochastic model for the surface topography of polygonal tundra using Poisson-Voronoi diagrams and we compare the results with available recent field studies. We analyze seasonal dynamics of water table variations and the landscape response under different scenarios of precipitation income. We upscale methane fluxes by using a simple idealized model for methane emission. Hydraulic interconnectivities and large-scale drainage may also be investigated through percolation properties and thresholds in the Voronoi graph. The model captures the main statistical characteristics of the landscape topography, such as polygon area and surface properties as well as the water balance. This approach enables us to statistically relate large-scale properties of the system to the main small-scale processes within the single polygons.

Bones collection of Lena Delta reserve Tiksi, Appendix 4-6

Remains of large Pleistocene mammals always attract attention. Scientists and local people who work and live in the Laptev Sea Region find and collect various bones and fragments of large mammals. Some of them are brought to the Lena Delta Reserve. Mammal remains of the "Mammoth fauna" are the most common artifacts in the paleontological collection of the Lena Delta Reserve museum. The collection includes single bones, fragments of skeletons, bones with soft tissues and hair of Late Pleistocene and Holocene specimens. It consists of nearly 300 samples. The museum was created thanks to the enthusiasm of Dr. A. Gukov, the present director of the reserve. Employees of the reserve, school teachers, pupils and other interested people also contribute. The first specimens were collected in 1985. They were bison bones collected by Yarlykov Yu. A. on Makar Island (Yana Delta Region) near the Makar polar station; Efimov S. N. found horse and reindeer bones on the Myostakh Cape, Bykovsky Peninsula (Lena Delta Region). Mammoth and reindeer bones were collected by Gukov A. Yu. during the same year on Kurungnakh-Sise Island. Over more than 20 years many people have presented their finds to the reserve. These are samples from different islands of the Lena Delta Region, from the New Siberian Islands, from the Yana Delta Region, and from the southern coasts of the Laptev and East Siberian Seas. Most of the collection consists of bones from the Bykovsky Peninsula (about 100 samples) as well as from the islands of the Lena Delta Region. Unfortunately not all samples have exact information about their origins or is geological information available for all finds. It is typical for this exhibition that the finds were collected by amateurs (not during geological or paleontological expeditions). A considerable portion of the collection consists of finds of Dr. A. Gukov from different locations within the Lena Delta Reserve. In 2001 Dr. A. Sher delivered about 40 samples from the Bykovsky Peninsula (Mamontovy Khayata) to the museum.