Systematic Time Resolution Measurements of Prototype Plastic Scintillator Bars with Photomultiplier Readout for the NeuLAND Detector
- The following thesis is the description and the analysis of time resolution measurements of the plastic scintillator protorypes bar with PMT (photomultiplier tube) readout, performed with a 31 MeV electron beam at the HZDR (Helmholtz-Zentrum Dresden-Rossendorf) . Similar bars will be used as building blocks for the NeuLAND detector (new large area neutron detector) - a ToF (time of flight) wall within the R3B setup (Reactions with Relativistic Radioactive Beams ) at the future FAIR facility (GSI Darmstadt ). The superconducting ELBE (electron linear-accellerator for beams of high brilliance and low emittance) was used as an electron source. The scintillation material used was RP408.
Two series of measurements were made within three months. In the first series, three bars of different sizes (200 x 5 x 5 cm3; 200 x 3 x 3 cm3; 300 x 5 x 5 cm3, the latter was made by coupling one 100 cm bar with a 200 cm bar using silicon grease) were used in the experiment consecutively. They had one Hamamatsu R8619 photomultiplier tube with an active diameter of 22 mm attached to each side with silicon grease. A measurement with the 200 x 5 x 5 cm3 bar without silicon grease was also performed.
In the second series, two equal scintillator bars (270 x 5 x 5 cm3 with a 10 cm light guide) on each side were used. Measurements with and without silicon coupling as well as with two different types of PMTs (R8619 and R2059) were executed.
Time and charge signals were processed with the TACQUILA electronic board. The time resolution was measured with the very precise pulsed electron signal of the accelerator. The time resolution measurements resulted in ρ200x5x5 ~ 159 ps; ρ200x5x5,no silicon ~ 162 ps; ρ200x3x3 ~ 153 ps; ρ300x5x5 ~ 204 ps.
For the second date they resulted in ρR8619 ~ 149 ps; ρR8619, no silicon ~ 175 ps; ρR2059 ~ 141 ps.
More tests and analysis is required until the results are definite.
Luis Kutner and the development of the advance directive (living will)
- It is well known that Luis Kutner (1908-1993) played an important role in the development of the living will (advance directive, Patientenverfügung). But it is not clear when he developed his concept. We have screened the Luis Kutner Papers,deposited at the Hoover Institution Archives at Stanford University to answer this question. We found out that in the second half of 1967, Kutner dealt intensively with the issue of euthanasia. On December 7, 1967, he delivered a speech at the annual meeting of the Euthanasia Society in New York and presented the concept of the living will to the audience. So Kutner surely was a pioneer in this field, but further research is necessary to clarify, if he (or maybe Elsa W. Simon or Abraham L. Wolbarst) was the "originator" of the living will concept in the sense of passive euthanasia.
Molecular Characterization of the Na+/H+-Antiporter NhaA from Salmonella Typhimurium
Christopher J. Lentes
Syed H. Mir
- Na+/H+ antiporters are integral membrane proteins that are present in almost every cell and in every kingdom of life. They are essential for the regulation of intracellular pH-value, Na+-concentration and cell volume. These secondary active transporters exchange sodium ions against protons via an alternating access mechanism, which is not understood in full detail. Na+/H+ antiporters show distinct species-specific transport characteristics and regulatory properties that correlate with respective physiological functions. Here we present the characterization of the Na+/H+ antiporter NhaA from Salmonella enterica serovar Thyphimurium LT2, the causing agent of food-born human gastroenteritis and typhoid like infections. The recombinant antiporter was functional in vivo and in vitro. Expression of its gene complemented the Na+-sensitive phenotype of an E. coli strain that lacks the main Na+/H+ antiporters. Purified to homogeneity, the antiporter was a dimer in solution as accurately determined by size-exclusion chromatography combined with multi-angle laser-light scattering and refractive index monitoring. The purified antiporter was fully capable of electrogenic Na+(Li+)/H+-antiport when reconstituted in proteoliposomes and assayed by solid-supported membrane-based electrophysiological measurements. Transport activity was inhibited by 2-aminoperimidine. The recorded negative currents were in agreement with a 1Na+(Li+)/2H+ stoichiometry. Transport activity was low at pH 7 and up-regulation above this pH value was accompanied by a nearly 10-fold decrease of KmNa (16 mM at pH 8.5) supporting a competitive substrate binding mechanism. K+ does not affect Na+ affinity or transport of substrate cations, indicating that selectivity of the antiport arises from the substrate binding step. In contrast to homologous E. coli NhaA, transport activity remains high at pH values above 8.5. The antiporter from S. Typhimurium is a promising candidate for combined structural and functional studies to contribute to the elucidation of the mechanism of pH-dependent Na+/H+ antiporters and to provide insights in the molecular basis of species-specific growth and survival strategies.
Cross-cultural color-odor associations
Carmel A. Levitan
Andy T. Woods
Jason S. Chan
Kirsten J. McKenzie
Jai A. Levin
Christine X. R. Leong
Jasper J. F. van den Bosch
- Colors and odors are associated; for instance, people typically match the smell of strawberries to the color pink or red. These associations are forms of crossmodal correspondences. Recently, there has been discussion about the extent to which these correspondences arise for structural reasons (i.e., an inherent mapping between color and odor), statistical reasons (i.e., covariance in experience), and/or semantically-mediated reasons (i.e., stemming from language). The present study probed this question by testing color-odor correspondences in 6 different cultural groups (Dutch, Netherlands-residing-Chinese, German, Malay, Malaysian-Chinese, and US residents), using the same set of 14 odors and asking participants to make congruent and incongruent color choices for each odor. We found consistent patterns in color choices for each odor within each culture, showing that participants were making non-random color-odor matches. We used representational dissimilarity analysis to probe for variations in the patterns of color-odor associations across cultures; we found that US and German participants had the most similar patterns of associations, followed by German and Malay participants. The largest group differences were between Malay and Netherlands-resident Chinese participants and between Dutch and Malaysian-Chinese participants. We conclude that culture plays a role in color-odor crossmodal associations, which likely arise, at least in part, through experience.
ND3, ND1 and 39kDa subunits are more exposed in the de-active form of bovine mitochondrial complex I
Catherine H. Botting
- An intriguing feature of mitochondrial complex I from several species is the so-called A/D transition, whereby the idle enzyme spontaneously converts from the active (A) form to the de-active (D) form. The A/D transition plays an important role in tissue response to the lack of oxygen and hypoxic deactivation of the enzyme is one of the key regulatory events that occur in mitochondria during ischaemia. We demonstrate for the first time that the A/D conformational change of complex I does not affect the macromolecular organisation of supercomplexes in vitro as revealed by two types of native electrophoresis. Cysteine 39 of the mitochondrially-encoded ND3 subunit is known to become exposed upon de-activation. Here we show that even if complex I is a constituent of the I+III2+IV (S1) supercomplex, cysteine 39 is accessible for chemical modification in only the D-form. Using lysine-specific fluorescent labelling and a DIGE-like approach we further identified two new subunits involved in structural rearrangements during the A/D transition: ND1 (MT-ND1) and 39kDa (NDUFA9). These results clearly show that structural rearrangements during de-activation of complex I include several subunits located at the junction between hydrophilic and hydrophobic domains, in the region of the quinone binding site. De-activation of mitochondrial complex I results in concerted structural rearrangement of membrane subunits which leads to the disruption of the sealed quinone chamber required for catalytic turnover.
Memory Concerns, Memory Performance and Risk of Dementia in Patients with Mild Cognitive Impairment
Friedel M. Reischies
- Background: Concerns about worsening memory (“memory concerns”; MC) and impairment in memory performance are both predictors of Alzheimer's dementia (AD). The relationship of both in dementia prediction at the pre-dementia disease stage, however, is not well explored. Refined understanding of the contribution of both MC and memory performance in dementia prediction is crucial for defining at-risk populations. We examined the risk of incident AD by MC and memory performance in patients with mild cognitive impairment (MCI).
Methods: We analyzed data of 417 MCI patients from a longitudinal multicenter observational study. Patients were classified based on presence (n = 305) vs. absence (n = 112) of MC. Risk of incident AD was estimated with Cox Proportional-Hazards regression models.
Results: Risk of incident AD was increased by MC (HR = 2.55, 95%CI: 1.33–4.89), lower memory performance (HR = 0.63, 95%CI: 0.56–0.71) and ApoE4-genotype (HR = 1.89, 95%CI: 1.18–3.02). An interaction effect between MC and memory performance was observed. The predictive power of MC was greatest for patients with very mild memory impairment and decreased with increasing memory impairment.
Conclusions: Our data suggest that the power of MC as a predictor of future dementia at the MCI stage varies with the patients' level of cognitive impairment. While MC are predictive at early stage MCI, their predictive value at more advanced stages of MCI is reduced. This suggests that loss of insight related to AD may occur at the late stage of MCI.
Knowledge, Attitude and Practice Regarding Dengue Fever among the Healthy Population of Highland and Lowland Communities in Central Nepal
Krishna Kumar Aryal
Mandira Lamichhane Dhimal
Shanker Pratap Singh
Chop Lal Bhusal
- BACKGROUND: Dengue fever (DF) is the most rapidly spreading mosquito-borne viral disease in the world. In this decade it has expanded to new countries and from urban to rural areas. Nepal was regarded DF free until 2004. Since then dengue virus (DENV) has rapidly expanded its range even in mountain regions of Nepal, and major outbreaks occurred in 2006 and 2010. However, no data on the local knowledge, attitude and practice (KAP) of DF in Nepal exist although such information is required for prevention and control measures.
METHODS: We conducted a community based cross-sectional survey in five districts of central Nepal between September 2011 and February 2012. We collected information on the socio-demographic characteristics of the participants and their knowledge, attitude and practice regarding DF using a structured questionnaire. We then statistically compared highland and lowland communities to identify possible causes of observed differences.
PRINCIPAL FINDINGS: Out of 589 individuals interviewed, 77% had heard of DF. Only 12% of the sample had good knowledge of DF. Those living in the lowlands were five times more likely to possess good knowledge than highlanders (P<0.001). Despite low knowledge levels, 83% of the people had good attitude and 37% reported good practice. We found a significantly positive correlation among knowledge, attitude and practice (P<0.001). Among the socio-demographic variables, the education level of the participants was an independent predictor of practice level (P<0.05), and education level and interaction between the sex and age group of the participants were independent predictors of attitude level (P<0.05).
CONCLUSION: Despite the rapid expansion of DENV in Nepal, the knowledge of people about DF was very low. Therefore, massive awareness programmes are urgently required to protect the health of people from DF and to limit its further spread in this country.
The competition effect in business cycles : [Version 9 März 2012]
- How do changes in market structure affect the US business cycle? We estimate a monetary DSGE model with endogenous
rm/product entry and a translog expenditure function by Bayesian methods. The dynamics of net business formation allow us to identify the 'competition effect', by which desired price markups and inflation decrease when entry rises. We
find that a 1 percent increase in the number of competitors lowers desired markups by 0.18 percent. Most of the cyclical variability in inflation is driven by markup fluctuations due to sticky prices or exogenous shocks rather than endogenous changes in desired markups.
Coulomb dissociation reactions on molybdenum isotopes for astrophysics applications
- Within the present work, photodissociation reactions on 100Mo, 93Mo and 92Mo isotopes were studied by means of the Coulomb dissociation method at the LAND setup at GSI. Experimental data on these isotopes are important to explain the problem of the underproduction of the lighter p-nuclei - 92; 94Mo - within the models of the p-process nucleosynthesis. The reaction rates used in the nucleosynthesis calculations are usually obtained within the framework of the statistical model. In order to verify the model predictions and reduce the uncertainties, experimental measurements of the reaction cross sections are required. In particular, the data on (γ,n) reactions are of interest, since these reactions were shown to dominate the p-process flow in the molybdenum mass region.
As a result of the analysis of the present experiment, integrated Coulomb excitation cross sections of the 100Mo(γ,n), 100Mo(γ,2n), 93Mo(γ,n) and 92Mo(γ,n) reactions were determined. The measurement of the 93Mo isotope is particularly important, since this nucleus is unstable, and the corresponding cross section has not been measured before.
It should be emphasized that Coulomb dissociation is a unique tool to study photoninduced reactions on unstable nuclei, which is especially relevant in the context of nucleosynthesis network calculations. However, because of to the complexity of the data analysis procedure and a number of model assumptions that are required in order to extract the Coulomb excitation cross section from the data, one of the main aspects of this thesis was to verify the method by comparing the results with the previously published data obtained with real photon beams. Integrated cross sections of the 100Mo(γ,n) and 100Mo(γ,2n) reactions were directly compared to the data by Beil et al., obtained at Saclay with photons from positron annihilation, while an indirect comparison could be performed with a recent photoactivation measurement by Erhard and co-workers. A reasonable agreement was observed for the 1n channel: a scaling factor of 0.8 ± 0.1 between our result and Beil et al. data is consistent with the scaling factor of 0.89±0.09 reported by Erhard et al. between their data and Beil et al. data. Both results are in agreement with the scaling factor of 0.85 ± 0.03 recommended by Berman et al. for the data measured at Saclay on nuclei in the respective mass region. A somewhat lower factor of 0.61 ± 0.09 between the present data and Beil et al. data was obtained for the 2n channel. The discrepancy might be explained by both the substantial efficiency correction that has to be applied to the LAND data in the two-neutron case, as well as by an insufficiently accurate assumption that the Saclay neutron detector efficiency is energy- and multiplicity- independent.
A second important topic of the present thesis is the investigation of the efficiency of the CsI gamma detector. The calorimetric information that it delivers is essential to reconstruct the energy-differential cross section from the present measurement. The data taken with the gamma calibration sources shortly after the experiment were used for the investigation. In addition, a test experiment in refined conditions was conducted within the framework of this thesis. Numerous GEANT3 simulations of the detector were performed in order to understand various aspects of its performance. As a result, the efficiency of the detector was determined to be approximately a factor of 2 lower than the efficiency expected from the simulation. This result is consistent with several independent investigations, which were performed using different methods. At the same time, a remarkable agreement between the simulated and experimental data was achieved under assumption that the inefficiency of the detector is explained by the loss of data from a number of crystals, which are randomly chosen in each event according to their averaged performance ratio (the ”on-off” effect). The reasons for the observed malfunction are yet not fully clear. Regardless of the exact reason, in the present conditions a deconvolution of the measured data from the CsI response is not possible. Consequently, within the framework of this thesis, the results are presented in terms of integrated cross sections. A search for alternative methods of data interpretation, allowing to extract energy-differential information out of the available data, in currently ongoing.
In the more recent experiments at the LAND setup, where the Crystal Ball gamma detector was used as a calorimeter, the reconstruction of the energy-differential cross section with a reasonable resolution was already shown to be feasible. It means that, even considering the uncertainties of the present experiment of the order of 10%, the uncertainties of the statistical model predictions, which are on average estimated to be within a factor of 1.5-2, can already be constrained.
The analysis of the present experiment is still in progress. As a next step, Coulomb excitation cross section for 94Mo will be obtained. The 94Mo(γ,n) reaction cannot be studied by photoactivation, since the life time of the daughter nucleus is too long (4000 y). At the same time, this reaction plays a key role in the p-process nucleosynthesis.
The future of the LAND setup - the R3B setup1 at FAIR2 - will take advantage of a three orders of magnitude higher intensity of the radioactive beams , as well as of a completely new detector system. High-resolution measurements of the energy-differential cross sections will be possible for exotic nuclei, which were never accessible in the laboratory before. Such measurements will open great opportunities for nuclear astrophysics, allowing to obtain high-quality experimental data even for regions of the nuclear chart where the statistical model calculations are not applicable.
Sustained release of triamcinolone acetonide from an intratympanically applied hydrogel designed for the delivery of high glucocorticoid doses
- The pharmacokinetic properties and tolerability of a triamcinolone acetonide poloxamer 407 hydrogel for intratympanic application were investigated in a guinea pig model. Evaluation of in vivo release kinetics showed very high initial perilymph drug levels, with clinically relevant levels present for a minimum of 10 days. Assessment of auditory brainstem response thresholds showed a minimal, delayed and transient threshold shift, which was apparent on day 3 and resolved by day 10. No relevant histological changes of the middle and inner ear structures were noted, and hair cell counts showed no significant differences between treated and untreated ears. Thus, the triamcinolone-acetonide-loaded poloxamer 407 hydrogel is an effective vehicle for sustained high-dose inner ear glucocorticoid delivery.