951 resultados para Independent Order of Odd Fellows. Pennsylvania. Grand Lodge.
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The gill monogene communities of Pimephales promelas (fathead minnow) in three distinct sites on converging streams were investigated from 2004 to 2006 in three different seasons. Thirty collections of P. promelas were made in southeastern Nebraska along three converging tributaries: Elk Creek (40.88534°N, 96.83366°W), West Oak Creek (40.9082°N, 96.81432°W), and Oak Creek (40.91402°N, 96.770583°W), Lancaster County, Nebraska. In all, 103 P. promelas were collected from Elk Creek, 115 from West Oak Creek, and 78 from Oak Creek and examined for gill monogenes. Among the P. promelas collected, 93.5% were infected with up to three species of Dactylogyrus, including Dactylogyrus simplex Mizelle, 1937, Dactylogyrus bychowskyi Mizelle, 1937, and Dactylogyrus pectenatus Mayes, 1977. Mean intensities at Elk Creek, West Oak Creek, and Oak Creek were 17.6, 22.8, and 25.1, and prevalences 88, 95, and 97%, respectively. At these three sites: (1) P. promelas does not share Dactylogyrus species with Semotilus atromaculatus (creek chub) or Notropis stramineus (sand shiner); (2) fish size and sex are not predictive of Dactylogyrus infection; (3) Dactylogyrus spp. vary (not always predictably) in their seasonal occurrence; (4) populations of Dactylogyrus spp. respond to environmental differences among sites; and (5) the community structure of Dactylogyrus spp. (order of abundance) is independent of environment.
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Using theoretical arguments, a simple scaling law for the size of the intrinsic rotation observed in tokamaks in the absence of a momentum injection is found: The velocity generated in the core of a tokamak must be proportional to the ion temperature difference in the core divided by the plasma current, independent of the size of the device. The constant of proportionality is of the order of 10 km . s(-1) . MA . keV(-1). When the intrinsic rotation profile is hollow, i.e., it is countercurrent in the core of the tokamak and cocurrent in the edge, the scaling law presented in this Letter fits the data remarkably well for several tokamaks of vastly different size and heated by different mechanisms.
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Let G be a group such that, for any subgroup H of G, every automorphism of H can be extended to an automorphism of G. Such a group G is said to be of injective type. The finite abelian groups of injective type are precisely the quasi-injective groups. We prove that a finite non-abelian group G of injective type has even order. If, furthermore, G is also quasi-injective, then we prove that G = K x B, with B a quasi-injective abelian group of odd order and either K = Q(8) (the quaternion group of order 8) or K = Dih(A), a dihedral group on a quasi-injective abelian group A of odd order coprime with the order of B. We give a description of the supersoluble finite groups of injective type whose Sylow 2-subgroup are abelian showing that these groups are, in general, not quasi-injective. In particular, the characterisation of such groups is reduced to that of finite 2-groups that are of injective type. We give several restrictions on the latter. We also show that the alternating group A(5) is of injective type but that the binary icosahedral group SL(2, 5) is not.
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Glossoscolex paulistus hemoglobin (HbGp) was studied by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). DLS melting curves were measured for met-HbGp at different concentrations. SAXS temperature studies were performed for oxy-, cyanomet- and met-HbGp forms, at several pH values. At pH 5.0 and 6.0, the scattering curves are identical from 20 to 60 degrees C, and R-g is 108 angstrom, independent of the oxidation form. At pH 7.0, protein denaturation and aggregation occurs above 55 degrees C and 60 degrees C, for oxy and met-HbGp, respectively. Cyanomet-HbGp, at pH 7.0, is stable up to 60 degrees C. At alkaline pH (8.0-9.0) and higher temperature, an irreversible dissociation process is observed, with a decrease of R-g, D-max and I(0). Analysis by p(r), obtained from GNOM, and OLIGOMER, was used to fit the SAXS experimental scattering curves by a combination of theoretical curves obtained for HbLt fragments from the crystal structure. Our results show clearly the increasing contribution of smaller molecular weight fragments, as a function of increasing pH and temperature, as well as, the order of thermal stabilities: cyanomet-> oxy- > met-HbGp. (C) 2012 Elsevier B.V. All rights reserved.
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Mannan-binding lectin (MBL) is an important protein of the innate immune system and protects the body against infection through opsonization and activation of the complement system on surfaces with an appropriate presentation of carbohydrate ligands. The quaternary structure of human MBL is built from oligomerization of structural units into polydisperse complexes typically with three to eight structural units, each containing three lectin domains. Insight into the connection between the structure and ligand-binding properties of these oligomers has been lacking. In this article, we present an analysis of the binding to neoglycoprotein-coated surfaces by size-fractionated human MBL oligomers studied with small-angle x-ray scattering and surface plasmon resonance spectroscopy. The MBL oligomers bound to these surfaces mainly in two modes, with dissociation constants in the micro to nanomolar order. The binding kinetics were markedly influenced by both the density of ligands and the number of ligand-binding domains in the oligomers. These findings demonstrated that the MBL-binding kinetics are critically dependent on structural characteristics on the nanometer scale, both with regard to the dimensions of the oligomer, as well as the ligand presentation on surfaces. Therefore, our work suggested that the surface binding of MBL involves recognition of patterns with dimensions on the order of 10-20 nm. The recent understanding that the surfaces of many microbes are organized with structural features on the nanometer scale suggests that these properties of MBL ligand recognition potentially constitute an important part of the pattern-recognition ability of these polyvalent oligomers. The Journal of Immunology, 2012, 188: 1292-1306.
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Unpolarized cross sections and double-helicity asymmetries of single-inclusive positive and negative charged hadrons at midrapidity from p + p collisions at root s = 62.4 GeV are presented. The PHENIX measurement of the cross sections for 1.0 < p(T) < 4.5 GeV/c are consistent with perturbative QCD calculations at next-to-leading order in the strong-coupling constant, alpha(s). Resummed pQCD calculations including terms with next-to-leading-log accuracy, yielding reduced theoretical uncertainties, also agree with the data. The double-helicity asymmetry, sensitive at leading order to the gluon polarization in a momentum-fraction range of 0.05 less than or similar to x(gluon) less than or similar to 0.2, is consistent with recent global parametrizations disfavoring large gluon polarization.
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The two main tools to determine the dynamical and physical parameters of exoplanet systems are the radial velocity (RV) measurements and, when available, transit timings. The two techniques are complementary: The RV's allow us to know some of the orbital elements while the transit timings allow us to obtain the orbital inclination and planetary radius, impossible of obtain from the RV, and to resolve the indetermination in the determination of the planet mass from the RV's. The space observation of transiting planets is however not limited to transit times. They extend to long periods of time and are precise enough to provide information on variations along the orbit. Besides the effects of stellar rotation, deserve mention the Doppler shift in the radiation flux, as consequence of stellar movement around the center of mass, or Beaming Effect (BE); the Ellipsoidal Variability (EV) due to the tidal deformation of the star due to the gravitation of its close companion; and the Reflection (ER) of the stellar radiation incident on the planet and re-emitted to the observer. In the case of large hot Jupiters, these effects are enhanced by the strong gravitational interaction and the analysis of the light variation allows us independent estimates of the mass and radius of planet. The planetary system CoRoT 3 is favorable for such analysis. In this case, the secondary is a brown dwarf whose mass is of the order of 22Mj. We show results obtained from the analysis of 35 RV measurements, 236999 photometric observations and 11 additional RV observations made during a transit to determine the star rotation via the Rossiter-McLaughlin effect. The results obtained from this determination are presented in this communication. The results are compared to those resulting from other determinations.
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[EN] This paper deals with the study of some new properties of the intrinsic order graph. The intrinsic order graph is the natural graphical representation of a complex stochastic Boolean system (CSBS). A CSBS is a system depending on an arbitrarily large number n of mutually independent random Boolean variables. The intrinsic order graph displays its 2n vertices (associated to the CSBS) from top to bottom, in decreasing order of their occurrence probabilities. New relations between the intrinsic ordering and the Hamming weight (i.e., the number of 1-bits in a binary n-tuple) are derived. Further, the distribution of the weights of the 2n nodes in the intrinsic order graph is analyzed…
Resumo:
Cytochrome P450 1A1 (CYP1A1) monooxygenase plays an important role in the metabolism of environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs) and halogenated polycyclic aromatic hydrocarbons (HAHs). Oxidation of these compounds converts them to the metabolites that subsequently can be conjugated to hydrophilic endogenous entities e.g. glutathione. Derivates generated in this way are water soluble and can be excreted in bile or urine, which is a defense mechanism. Besides detoxification, metabolism by CYP1A1 may lead to deleterious effects since the highly reactive intermediate metabolites are able to react with DNA and thus cause mutagenic effects, as it is in the case of benzo(a) pyrene (B[a]P). CYP1A1 is normally not expressed or expressed at a very low level in the cells but it is inducible by many PAHs and HAHs e.g. by B[a]P or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Transcriptional activation of the CYP1A1 gene is mediated by aryl hydrocarbon receptor (AHR), a basic-helix-loop-helix (bHLH) transcription factor. In the absence of a ligand AHR stays predominantly in the cytoplasm. Ligand binding causes translocation of AHR to the nuclear compartment, its heterodimerization with another bHLH protein, the aryl hydrocarbon nuclear translocator (ARNT) and binding of the AHR/ARNT heterodimer to a DNA motif designated dioxin responsive element (DRE). This process leads to the transcriptional activation of the responsive genes containing DREs in their regulatory regions, e.g. that coding for CYP1A1. TCDD is the most potent known agonist of AHR. Since it is not metabolized by the activated enzymes, exposure to this compound leads to a persisting activation of AHR resulting in diverse toxic effects in the organism. To enlighten the molecular mechanisms that mediate the toxicity of xenobiotics like TCDD and related compounds, the AHR-dependent regulation of the CYP1A1 gene was investigated in two cell lines: human cervix carcinoma (HeLa) and mouse hepatoma (Hepa). Study of AHR activation and its consequence concerning expression of the CYP1A1 enzyme confirmed the TCDD-dependent formation of the AHR/ARNT complex on DRE leading to an increase of the CYP1A1 transcription in Hepa cells. In contrast, in HeLa cells formation of the AHR/ARNT heterodimer and binding of a protein complex containing AHR and ARNT to DRE occurred naturally in the absence of TCDD. Moreover, treatment with TCDD did not affect the AHR/ARNT dimer formation and binding of these proteins to DRE in these cells. Even though the constitutive complex on DRE exists in HeLa, transcription of the CYP1A1 gene was not increased. Furthermore, the CYP1A1 level in HeLa cells remained unchanged in the presence of TCDD suggesting repressional mechanism of the AHR complex function which may hinder the TCDD-dependent mechanisms in these cells. Similar to the native, the mouse CYP1A1-driven reporter constructs containing different regulatory elements were not inducible by TCDD in HeLa cells, which supported a presence of cell type specific trans-acting factor in HeLa cells able to repress both the native CYP1A1 and CYP1A1-driven reporter genes rather than species specific differences between CYP1A1 genes of human and rodent origin. The different regulation of the AHR-mediated transcription of CYP1A1 gene in Hepa and HeLa cells was further explored in order to elucidate two aspects of the AHR function: (I) mechanism involved in the activation of AHR in the absence of exogenous ligand and (II) factor that repress function of the exogenous ligand-independent AHR/ARNT complex. Since preliminary studies revealed that the activation of PKA causes an activation of AHR in Hepa cells in the absence of TCDD, the PKA-dependent signalling pathway was the proposed endogenous mechanism leading to the TCDD-independent activation of AHR in HeLa cells. Activation of PKA by forskolin or db-cAMP as well as inhibition of the kinase by H89 in both HeLa and Hepa cells did not lead to alterations in the AHR interaction with ARNT in the absence of TCDD and had no effect on binding of these proteins to DRE. Moreover, the modulators of PKA did not influence the CYP1A1 activity in these cells in the presence and in the absence of TCDD. Thus, an involvement of PKA in the regulation of the CYP1A1 Gen in HeLa cells was not evaluated in the course of this study. Repression of genes by transcription factors bound to their responsive elements in the absence of ligands has been described for nuclear receptors. These receptors interact with protein complex containing histone deacetylase (HDAC), enzyme responsible for the repressional effect. Thus, a participation of histone deacetylase in the transcriptional modulation of CYP1A1 gene by the constitutively DNA-bound AHR/ARNT complex was supposed. Inhibition of the HDAC activity by trichostatin A (TSA) or sodium butyrate (NaBu) led to an increase of the CYP1A1 transcription in the presence but not in the absence of TCDD in Hepa and HeLa cells. Since amount of the AHR and ARNT proteins remained unchanged upon treatment of the cells with TSA or NaBu, the transcriptional upregulation of CYP1A1 gene was not due to an increased expression of the regulatory proteins. These findings strongly suggest an involvement of HDAC in the repression of the CYP1A1 gene. Similar to the native human CYP1A1 also the mouse CYP1A1-driven reporter gene transfected into HeLa cells was repressed by histone deacetylase since the presence of TSA or NaBu led to an increase in the reporter activity. Induction of reporter gene did not require a presence of the promoter or negative regulatory regions of the CYP1A1 gene. A promoter-distal fragment containing three DREs together with surrounding sequences was sufficient to mediate the effects of the HDAC inhibitors suggesting that the AHR/ARNT binding to its specific DNA recognition site may be important for the CYP1A1 repression. Histone deacetylase is recruited to the specific genes by corepressors, proteins that bind to the transcription factors and interact with other members of the HDAC complex. Western blot analyses revealed a presence of HDAC1 and the corepressors mSin3A (mammalian homolog of yeast Sin3) and SMRT (silencing mediator for retinoid and thyroid hormone receptor) in both cell types, while the corepressor NCoR (nuclear receptor corepressor) was expressed exclusively in HeLa cells. Thus the high inducibility of CYP1A1 in Hepa cells may be due to the absence of NCoR in these cells in contrast to the non-responsive HeLa cells, where the presence of NCoR would support repression of the gene by histone deacetylase. This hypothesis was verified in reporter gene experiments where expression constructs coding for the particular members of the HDAC complex were cotransfected in Hepa cells together with the TCDD-inducible reporter constructs containing the CYP1A1 regulatory sequences. An overexpression of NCoR however did not decrease but instead led to a slight increase of the reporter gene activity in the cells. The expected inhibition was observed solely in the case of SMRT that slightly reduced constitutive and TCDD-induced reporter gene activity. A simultaneous expression of NCoR and SMRT shown no further effects and coexpression of HDAC1 with the two corepressors did not alter this situation. Thus, additional factors that are likely involved in the repression of CYP1A1 gene by HDAC complex remained to be identified. Taking together, characterisation of an exogenous ligand independent AHR/ARNT complex on DRE in HeLa cells that repress transcription of the CYP1A1 gene creates a model system enabling investigation of endogenous processes involved in the regulation of AHR function. This study implicates HDAC-mediated repression of CYP1A1 gene that contributes to the xenobiotic-induced expression in a tissue specific manner. Elucidation of these processes gains an insight into mechanisms leading to deleterious effects of TCDD and related compounds.
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Iodide transport is necessary for the synthesis of thyroid hormones following accumulation in the follicular lumen out of thyroid cells, via channels unknown with the exception of pendrin. According to our hypothesis, TMEM16A could be the main molecular identity of the channel mediating iodide efflux in the thyroid gland. TMEM16A is the prior candidate for calcium-activated chloride conductance (CaCC). TMEM16A belongs to the TMEM16/anoctamin family comprising ten members (TMEM16A-K). Higher affinity of TMEM16A for iodide and predicted expression in the thyroid gland suggest its mediation of iodide efflux. The aim of this project was to identify the role of TMEM16A in iodide transport in the thyroid gland, by characterizing its molecular expression and functional properties. We demonstrated that TMEM16F, H, K transcripts are expressed in FRTL-5 thyroid cells, as well as TMEM16A, which is TSH-independent. Tumor tissue from human thyroid maintains TMEM16A expression. Functional in vivo experiments in FRTL-5, stably expressing YFP-H148Q/I152L fluorescent protein as a biosensor, showed that iodide efflux is stimulated by agonists of purinergic receptors with an order of potency of ATP>UTP>ADP (compatible with an involvement of P2Y purinergic receptors), and by agonists of adrenergic receptors (epinephrine, norepinephrine and phenylephrine). Iodide efflux was blocked by α-receptor antagonists prazosin and phentolamine, consistent with a role of α1 adrenergic receptors. Iodide efflux was specifically dependent on calcium mobilized from intracellular compartments and induced by the calcium ionophore ionomycin. CaCC blockers suppressed ionomycin-/ATP-/epinephrine-stimulated iodide efflux. Heterologous expression of TMEM16A in CHO K1 cells induced calcium-activated iodide fluxes. All these results support the hypothesis of the involvement of TMEM16A in calcium-dependent iodide efflux induced by receptor agonists in thyroid cells. TMEM16A may represent a new pharmacological target for thyroid cancer therapy, since its blockade may enhance the retention of radioiodide by tumour cells enhancing the efficacy of radioablative therapy.
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The only nuclear model independent method for the determination of nuclear charge radii of short-lived radioactive isotopes is the measurement of the isotope shift. For light elements (Z < 10) extremely high accuracy in experiment and theory is required and was only reached for He and Li so far. The nuclear charge radii of the lightest elements are of great interest because they have isotopes which exhibit so-called halo nuclei. Those nuclei are characterized by a a very exotic nuclear structure: They have a compact core and an area of less dense nuclear matter that extends far from this core. Examples for halo nuclei are 6^He, 8^He, 11^Li and 11^Be that is investigated in this thesis. Furthermore these isotopes are of interest because up to now only for such systems with a few nucleons the nuclear structure can be calculated ab-initio. In the Institut für Kernchemie at the Johannes Gutenberg-Universität Mainz two approaches with different accuracy were developed. The goal of these approaches was the measurement of the isotope shifts between (7,10,11)^Be^+ and 9^Be^+ in the D1 line. The first approach is laser spectroscopy on laser cooled Be^+ ions that are trapped in a linear Paul trap. The accessible accuracy should be in the order of some 100 kHz. In this thesis two types of linear Paul traps were developed for this purpose. Moreover, the peripheral experimental setup was simulated and constructed. It allows the efficient deceleration of fast ions with an initial energy of 60 keV down to some eV and an effcient transport into the ion trap. For one of the Paul traps the ion trapping could already be demonstrated, while the optical detection of captured 9^Be^+ ions could not be completed, because the development work was delayed by the second approach. The second approach uses the technique of collinear laser spectroscopy that was already applied in the last 30 years for measuring isotope shifts of plenty of heavier isotopes. For light elements (Z < 10), it was so far not possible to reach the accuracy that is required to extract information about nuclear charge radii. The combination of collinear laser spectroscopy with the most modern methods of frequency metrology finally permitted the first-time determination of the nuclear charge radii of (7,10)^Be and the one neutron halo nucleus 11^Be at the COLLAPS experiment at ISOLDE/ CERN. In the course of the work reported in this thesis it was possible to measure the absolute transition frequencies and the isotope shifts in the D1 line for the Be isotopes mentioned above with an accuracy of better than 2 MHz. Combination with the most recent calculations of the mass effect allowed the extraction of the nuclear charge radii of (7,10,11)^Be with an relative accuracy better than 1%. The nuclear charge radius decreases from 7^Be continuously to 10^Be and increases again for 11^Be. This result is compared with predictions of ab-initio nuclear models which reproduce the observed trend. Particularly the "Greens Function Monte Carlo" and the "Fermionic Molecular Dynamic" model show very good agreement.
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Five different methods were critically examined to characterize the pore structure of the silica monoliths. The mesopore characterization was performed using: a) the classical BJH method of nitrogen sorption data, which showed overestimated values in the mesopore distribution and was improved by using the NLDFT method, b) the ISEC method implementing the PPM and PNM models, which were especially developed for monolithic silicas, that contrary to the particulate supports, demonstrate the two inflection points in the ISEC curve, enabling the calculation of pore connectivity, a measure for the mass transfer kinetics in the mesopore network, c) the mercury porosimetry using a new recommended mercury contact angle values. rnThe results of the characterization of mesopores of monolithic silica columns by the three methods indicated that all methods were useful with respect to the pore size distribution by volume, but only the ISEC method with implemented PPM and PNM models gave the average pore size and distribution based on the number average and the pore connectivity values.rnThe characterization of the flow-through pore was performed by two different methods: a) the mercury porosimetry, which was used not only for average flow-through pore value estimation, but also the assessment of entrapment. It was found that the mass transfer from the flow-through pores to mesopores was not hindered in case of small sized flow-through pores with a narrow distribution, b) the liquid penetration where the average flow-through pore values were obtained via existing equations and improved by the additional methods developed according to Hagen-Poiseuille rules. The result was that not the flow-through pore size influences the column bock pressure, but the surface area to volume ratio of silica skeleton is most decisive. Thus the monolith with lowest ratio values will be the most permeable. rnThe flow-through pore characterization results obtained by mercury porosimetry and liquid permeability were compared with the ones from imaging and image analysis. All named methods enable a reliable characterization of the flow-through pore diameters for the monolithic silica columns, but special care should be taken about the chosen theoretical model.rnThe measured pore characterization parameters were then linked with the mass transfer properties of monolithic silica columns. As indicated by the ISEC results, no restrictions in mass transfer resistance were noticed in mesopores due to their high connectivity. The mercury porosimetry results also gave evidence that no restrictions occur for mass transfer from flow-through pores to mesopores in the small scaled silica monoliths with narrow distribution. rnThe prediction of the optimum regimes of the pore structural parameters for the given target parameters in HPLC separations was performed. It was found that a low mass transfer resistance in the mesopore volume is achieved when the nominal diameter of the number average size distribution of the mesopores is appr. an order of magnitude larger that the molecular radius of the analyte. The effective diffusion coefficient of an analyte molecule in the mesopore volume is strongly dependent on the value of the nominal pore diameter of the number averaged pore size distribution. The mesopore size has to be adapted to the molecular size of the analyte, in particular for peptides and proteins. rnThe study on flow-through pores of silica monoliths demonstrated that the surface to volume of the skeletons ratio and external porosity are decisive for the column efficiency. The latter is independent from the flow-through pore diameter. The flow-through pore characteristics by direct and indirect approaches were assessed and theoretical column efficiency curves were derived. The study showed that next to the surface to volume ratio, the total porosity and its distribution of the flow-through pores and mesopores have a substantial effect on the column plate number, especially as the extent of adsorption increases. The column efficiency is increasing with decreasing flow through pore diameter, decreasing with external porosity, and increasing with total porosity. Though this tendency has a limit due to heterogeneity of the studied monolithic samples. We found that the maximum efficiency of the studied monolithic research columns could be reached at a skeleton diameter of ~ 0.5 µm. Furthermore when the intention is to maximize the column efficiency, more homogeneous monoliths should be prepared.rn
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Bivalve mollusk shells are useful tools for multi-species and multi-proxy paleoenvironmental reconstructions with a high temporal and spatial resolution. Past environmental conditions can be reconstructed from shell growth and stable oxygen and carbon isotope ratios, which present an archive for temperature, freshwater fluxes and primary productivity. The purpose of this thesis is the reconstruction of Holocene climate and environmental variations in the North Pacific with a high spatial and temporal resolution using marine bivalve shells. This thesis focuses on several different Holocene time periods and multiple regions in the North Pacific, including: Japan, Alaska (AK), British Columbia (BC) and Washington State, which are affected by the monsoon, Pacific Decadal Oscillation (PDO) and El Niño/Southern Oscillation (ENSO). Such high-resolution proxy data from the marine realm of mid- and high-latitudes are still rare. Therefore, this study contributes to the optimization and verification of climate models. However, before using bivalves for environmental reconstructions and seasonality studies, life history traits must be well studied to temporally align and interpret the geochemical record. These calibration studies are essential to ascertain the usefulness of selected bivalve species as paleoclimate proxy archives. This work focuses on two bivalve species, the short-lived Saxidomus gigantea and the long-lived Panopea abrupta. Sclerochronology and oxygen isotope ratios of different shell layers of P. abrupta were studied in order to test the reliability of this species as a climate archive. The annual increments are clearly discernable in umbonal shell portions and the increments widths should be measured in these shell portions. A reliable reconstruction of paleotemperatures may only be achieved by exclusively sampling the outer shell layer of multiple contemporaneous specimens. Life history traits (e.g., timing of growth line formation, duration of the growing season and growth rates) and stable isotope ratios of recent S. gigantea from AK and BC were analyzed in detail. Furthermore, a growth-temperature model based on S. gigantea shells from Alaska was established, which provides a better understanding of the hydrological changes related to the Alaska Coastal Current (ACC). This approach allows the independent measurement of water temperature and salinity from variations in the width of lunar daily growth increments of S. gigantea. Temperature explains 70% of the variability in shell growth. The model was calibrated and tested with modern shells and then applied to archaeological specimens. The time period between 988 and 1447 cal yrs BP was characterized by colder (~1-2°C) and much drier (2-5 PSU) summers, and a likely much slower flowing ACC than at present. In contrast, the summers during the time interval of 599-1014 cal yrs BP were colder (up to 3°C) and fresher (1-2 PSU) than today. The Aleutian Low may have been stronger and the ACC was probably flowing faster during this time.
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Lattice Quantum Chromodynamics (LQCD) is the preferred tool for obtaining non-perturbative results from QCD in the low-energy regime. It has by nowrnentered the era in which high precision calculations for a number of phenomenologically relevant observables at the physical point, with dynamical quark degrees of freedom and controlled systematics, become feasible. Despite these successes there are still quantities where control of systematic effects is insufficient. The subject of this thesis is the exploration of the potential of todays state-of-the-art simulation algorithms for non-perturbativelyrn$\mathcal{O}(a)$-improved Wilson fermions to produce reliable results in thernchiral regime and at the physical point both for zero and non-zero temperature. Important in this context is the control over the chiral extrapolation. Thisrnthesis is concerned with two particular topics, namely the computation of hadronic form factors at zero temperature, and the properties of the phaserntransition in the chiral limit of two-flavour QCD.rnrnThe electromagnetic iso-vector form factor of the pion provides a platform to study systematic effects and the chiral extrapolation for observables connected to the structure of mesons (and baryons). Mesonic form factors are computationally simpler than their baryonic counterparts but share most of the systematic effects. This thesis contains a comprehensive study of the form factor in the regime of low momentum transfer $q^2$, where the form factor is connected to the charge radius of the pion. A particular emphasis is on the region very close to $q^2=0$ which has not been explored so far, neither in experiment nor in LQCD. The results for the form factor close the gap between the smallest spacelike $q^2$-value available so far and $q^2=0$, and reach an unprecedented accuracy at full control over the main systematic effects. This enables the model-independent extraction of the pion charge radius. The results for the form factor and the charge radius are used to test chiral perturbation theory ($\chi$PT) and are thereby extrapolated to the physical point and the continuum. The final result in units of the hadronic radius $r_0$ is rn$$ \left\langle r_\pi^2 \right\rangle^{\rm phys}/r_0^2 = 1.87 \: \left(^{+12}_{-10}\right)\left(^{+\:4}_{-15}\right) \quad \textnormal{or} \quad \left\langle r_\pi^2 \right\rangle^{\rm phys} = 0.473 \: \left(^{+30}_{-26}\right)\left(^{+10}_{-38}\right)(10) \: \textnormal{fm} \;, $$rn which agrees well with the results from other measurements in LQCD and experiment. Note, that this is the first continuum extrapolated result for the charge radius from LQCD which has been extracted from measurements of the form factor in the region of small $q^2$.rnrnThe order of the phase transition in the chiral limit of two-flavour QCD and the associated transition temperature are the last unkown features of the phase diagram at zero chemical potential. The two possible scenarios are a second order transition in the $O(4)$-universality class or a first order transition. Since direct simulations in the chiral limit are not possible the transition can only be investigated by simulating at non-zero quark mass with a subsequent chiral extrapolation, guided by the universal scaling in the vicinity of the critical point. The thesis presents the setup and first results from a study on this topic. The study provides the ideal platform to test the potential and limits of todays simulation algorithms at finite temperature. The results from a first scan at a constant zero-temperature pion mass of about 290~MeV are promising, and it appears that simulations down to physical quark masses are feasible. Of particular relevance for the order of the chiral transition is the strength of the anomalous breaking of the $U_A(1)$ symmetry at the transition point. It can be studied by looking at the degeneracies of the correlation functions in scalar and pseudoscalar channels. For the temperature scan reported in this thesis the breaking is still pronounced in the transition region and the symmetry becomes effectively restored only above $1.16\:T_C$. The thesis also provides an extensive outline of research perspectives and includes a generalisation of the standard multi-histogram method to explicitly $\beta$-dependent fermion actions.
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Die Kontroverse über den Glasübergang im Nanometerbereich, z. B. die Glas¬über¬gangs-temperatur Tg von dünnen Polymerfilmen, ist nicht vollständig abgeschlossen. Das dynamische Verhalten auf der Nanoskala ist stark von den einschränkenden Bedingungen abhängig, die auf die Probe wirken. Dünne Polymerfilme sind ideale Systeme um die Dynamik von Polymerketten unter der Einwirkung von Randbedingungen zu untersuchen, wie ich sie in dieser Arbeit variiert habe, um Einblick in dieses Problem zu erhalten.rnrnResonanzverstärkte dynamische Lichtstreuung ist eine Methode, frei von z.B. Fluoreszenzmarkern, die genutzt werden kann um in dünnen Polymerfilmen dynamische Phänomene