Hrabanus Maurus, 776-856; a historical study of some aspects of medieval education.

Thesis (Ed.M.)--Boston Universit

Spectral transmittance of Christiansen filters - Experimental observations

Powder of the optical glass K5 has been immersed into methyl benzoate as refractice index matching fluid to fabricate Christiansen filters. The internal spectral transmittance of these filters has been investigated in the visible spectral region as a function of the filter thickness, the mean diameter of the powder grains, and the difference between the refractive indices of the fluid and the K5 glass. The minimum internal spectral extinction of the filter curve is approximately proportional to the thickness of the filter. Furthermore, it scales inversely with the average diameter of the glass grains. Hence, one can deduce that the minimum spectral extinction is proportional to the total interface area between grains and Immersion liquid. According to the experimental results it can be concluded further that this extinction is mainly due to Rayleigh scattering. The halfwidth of the spectral transmission passband decreases with increasing thickness of the filters and with decreasing average diameter of the grains. The spectral extinction at wavelengths sufficiently far from its minimum increases sublinearly with the filter thickness and the inverse mean diameter of the grains. In the same spectral region, the extinction increases also sublinearly with the absolute difference between the refractive indices of the matenal of the grains and of the Immersion liquid. Undl now, a theory predicting all of these observations correctly seems to be still missing

Milchprodukte aus biologisch-dynamischer Herkunft führen zu einer vorteilhafteren Fettzusammensetzung der menschlichen Muttermilch

In unserer früheren Studie konnten wir zeigen, dass der Verzeh biologischer Milchprodukte durch stillende Mütter zu einem erhöhten Gehalt an konjugierten Linolsäure-Isomeren in der Muttermilch führt, was sich positiv auf die Gesundheit des Säuglings auswirken kann. Nun wurde der Einfluss biologisch- dynamischer Milchprodukte in der Diät auf den konjugierten Linolsäure-Isomerengehalt in der menschlichen Muttermilch untersucht. Der Anteil an Rumensäure (das am meisten vorhandene Isomere) in der Muttermilch der Frauen, die biologisch-dynamische Milchprodukte zu sich nahmen, war statistisch signifikant höher (n = 64, 0,323% vom gesamten Fett) als derjenige der sich konventionell ernährenden Mütter (n = 175, 0,254%). Dabei zeigte die Muttermilch der Frauen, die biologische (aber nicht biologisch-dynamische) Milchprodukte zu sich nahmen, einen dazwischenliegenden Wert (n = 44, 0,279%). Die Varia- tionen in dem Rumensäuregehalten wurden von ähnlichen Schwankungen in den Gehalten der entsprechenden Vorstufe, der trans-Vaccensäure, begleitet. Der Gehalt an Elaidinsäure, die in teilgehärteten pflanzlichen Ölen in hohen Mengen vorkommt, verhielt sich umgekehrt. Ein möglicher Beitrag biologisch-dynamischer Milchprodukte zur Verbesserung der Gesundheit wird kurz besprochen

Influence of organic diet on the amount of conjugated linoleic acids in breast milk of lactating women in the Netherlands

The aim of the present study was to find out whether the incorporation of organic dairy and meat products in the maternal diet affects the contents of the conjugated linoleic acid isomers (CLA) and trans-vaccenic acid (TVA) in human breast milk. To this purpose, milk samples from 312 breastfeeding mothers participating in the KOALA Birth Cohort Study have been analysed. The participants had documented varying lifestyles in relation to the use of conventional or organic products. Breast milk samples were collected 1 month postpartum and analysed for fatty acid composition. The content of rumenic acid (the main CLA) increased in a statistically significant way while going from a conventional diet (no organic dairy/meat products, 0.25 weight % (wt%), n 186) to a moderately organic diet (50–90 % organic dairy/meat, 0·29 wt%, n 33, P=0.02) and to a strict organic diet (> 90 % organic dairy/meat, 0.34 wt%, n 37, P<=0.001). The levels of TVA were augmented among the participants with a moderately organic diet (0·54 wt%) and those with a strict organic diet (0.59 wt%, P<=0.001), in comparison with the conventional group (0·48 wt%). After adjusting for covariables (recruitment group, maternal age, maternal education, use of supplements and season), statistical significance was retained in the group of the strict organic dairy users (P<0.001 for rumenic acid). Hence, the levels of CLA and TVA in human milk can be modulated if breastfeeding mothers replace conventional dairy and/or meat products by organic ones. A potential contribution of CLA and TVA to health improvement is briefly discussed

Manipulating Semicrystalline Polymers in Confinement

Because final properties of nanoscale polymeric structures are largely determined by the solid-state microstructure of the confined polymer, it is imperative not only to understand how the microstructure of polymers develops under nanoscale confinement but also to establish means to manipulate it. Here we present a series of processing strategies, adapted from methods used in bulk polymer processing, that allow to control the solidification of polymer nanostructures. Firstly, we show that supramolecular nucleating agents can be readily used to modify the crystallization kinetics of confined poly(vinylidene fluoride) (PVDF). In addition, we demonstrate that microstructural features that are not traditionally affected by nucleating agents, such as the orientation of crystals, can be tuned with the crystallization temperature applied. Interestingly, we also show that high crystallization temperatures and long annealing periods induce the formation of the modification of PVDF, hence enabling the simple production of ferro/piezoelectric nanostructures. We anticipate that the approaches presented here can open up a plethora of new possibilities for the processing of polymer-based nanostructures with tailored properties and functionalities

Influence of organic diet on the amount of conjugated linoleic acids in breast milk of lactating women in the Netherlands

The aim of the present study was to find out whether the incorporation of organic dairy and meat products in the maternal diet affects the contents of the conjugated linoleic acid isomers (CLA) and trans-vaccenic acid (TVA) in human breast milk. To this purpose, milk samples from 312 breastfeeding mothers participating in the KOALA Birth Cohort Study have been analysed. The participants had documented varying lifestyles in relation to the use of conventional or organic products. Breast milk samples were collected 1month postpartum and analysed for fatty acid composition. The content of rumenic acid (the main CLA) increased in a statistically significant way while going from a conventional diet (no organic dairy/meat products, 0·25 weight % (wt%), n 186) to a moderately organic diet (50-90% organic dairy/meat, 0·29wt%, n 33, P=0·02) and to a strict organic diet (>90% organic dairy/meat, 0·34wt%, n 37, P≤0·001). The levels of TVA were augmented among the participants with a moderately organic diet (0·54wt%) and those with a strict organic diet (0·59wt%, P≤0·001), in comparison with the conventional group (0·48wt%). After adjusting for covariables (recruitment group, maternal age, maternal education, use of supplements and season), statistical significance was retained in the group of the strict organic dairy users (P<0·001 for rumenic acid). Hence, the levels of CLA and TVA in human milk can be modulated if breastfeeding mothers replace conventional dairy and/or meat products by organic ones. A potential contribution of CLA and TVA to health improvement is briefly discusse

Searches at HERA for Squarks in R-Parity Violating Supersymmetry

A search for squarks in R-parity violating supersymmetry is performed in e^+p collisions at HERA at a centre of mass energy of 300 GeV, using H1 data corresponding to an integrated luminosity of 37 pb^(-1). The direct production of single squarks of any generation in positron-quark fusion via a Yukawa coupling lambda' is considered, taking into account R-parity violating and conserving decays of the squarks. No significant deviation from the Standard Model expectation is found. The results are interpreted in terms of constraints within the Minimal Supersymmetric Standard Model (MSSM), the constrained MSSM and the minimal Supergravity model, and their sensitivity to the model parameters is studied in detail. For a Yukawa coupling of electromagnetic strength, squark masses below 260 GeV are excluded at 95% confidence level in a large part of the parameter space. For a 100 times smaller coupling strength masses up to 182 GeV are excluded.Comment: 32 pages, 14 figures, 3 table

Multiplicity Structure of the Hadronic Final State in Diffractive Deep-Inelastic Scattering at HERA

The multiplicity structure of the hadronic system X produced in deep-inelastic processes at HERA of the type ep -> eXY, where Y is a hadronic system with mass M_Y< 1.6 GeV and where the squared momentum transfer at the pY vertex, t, is limited to |t|<1 GeV^2, is studied as a function of the invariant mass M_X of the system X. Results are presented on multiplicity distributions and multiplicity moments, rapidity spectra and forward-backward correlations in the centre-of-mass system of X. The data are compared to results in e+e- annihilation, fixed-target lepton-nucleon collisions, hadro-produced diffractive final states and to non-diffractive hadron-hadron collisions. The comparison suggests a production mechanism of virtual photon dissociation which involves a mixture of partonic states and a significant gluon content. The data are well described by a model, based on a QCD-Regge analysis of the diffractive structure function, which assumes a large hard gluonic component of the colourless exchange at low Q^2. A model with soft colour interactions is also successful.Comment: 22 pages, 4 figures, submitted to Eur. Phys. J., error in first submission - omitted bibliograph