Some notes concerning the homogeneity of Boolean algebras and Boolean spaces

We consider homogeneity properties of Boolean algebras that have nonprincipal ultrafilters which are countably generated.It is shown that a Boolean algebra B is homogeneous if it is the union of countably generated nonprincipal ultrafilters and has a dense subset D such that for every a in D the relative algebra B restriction a:= {b in B:b <= a} is isomorphic to B. In particular, the free product of countably many copies of an atomic Boolean algebra is homogeneous. Moreover, a Boolean algebra B is homogeneous if it satisfies the following conditions: (i) B has a countably generated ultrafilter, (ii) B is not c.c.c., and (iii) for every a in B setminus {0} there are finitely many automorphisms h_1, ...,h_n of B such that 1=h_1(a) cup ... cup h_n(a)

The carbon footprint of desalination: An input-output analysis of seawater reverse osmosis desalination in Australia for 2005–2015

This study examines greenhouse gas emissions for 2005–2015 from seawater desalination in Australia, using conventional energies. We developed a tailor-made multi-regional input-output-model. We complemented macroeconomic top-down data with plant-specific desalination data of the largest 20 desalination plants in Australia. The analysed capacity cumulates to 95% of Australia's overall seawater desalination capacity. We considered the construction and the operation of desalination plants. We measure not only direct effects, but also indirect effects throughout the entire value chain. Our results show the following: We identify the state of Victoria with the highest emissions due to capital and operational expenditures (capex and opex). The contribution of the upstream value chain to total greenhouse gas emissions increases for capex and decreases for opex. For capex, the construction of intake and outfall is the driving factor for carbon emissions. For opex, electricity consumption is the decisive input factor. Both in construction and operation, we identify the critical role of the electricity sector for carbon emissions throughout the supply chain effects. The sector contributes 69% during the zenith of the construction phase and 96% during the operating phase to the entire emissions. We estimate the total emissions for 2015 at 1193 kt CO2e

Prejudice against and discrimination of asylum seekers: their antecedents and consequences in a longitudinal field study

Prejudice towards and discrimination of migrants are serious problems in our modern, globalised world. In the present doctoral thesis it was studied how negative attitudes of citizens towards asylum seekers relate to contact experiences, feelings of threat and acculturation orientations. A longitudinal field study with two measurement points was conducted with the German inhabitants (N = 70) of a neighbourhood where an asylum seekers refuge was soon to be opened. Directly before and six months after the opening of the refuge the attitudes (i.e., prejudice, negative emotions and discrimination intentions) of the locals towards the asylum seekers (and their contact experiences) were assessed with questionnaires. Several theoretical backgrounds were used for this study. First, drawing on theories from contact research, effects of three different kinds of contact were hypothesised. Improvements of attitudes towards migrants through mere contact (mere presence of the newcomers), personal contact (own contact experiences) and extended contact (knowledge of neighbours’ contact experiences) were analysed and compared. Secondly, perceptions of realistic and symbolic intergroup threat were related to outgroup attitudes. While some theories take stable personality traits (such as Authoritarianism or prejudice) as causal predictors of threat perceptions, other theories, such as the Integrated Threat Model, take threat perceptions as causal antecedents of prejudice. These contradicting claims were tested. Thirdly, acculturation orientations were related to attitudes and personal contact behaviour. Acculturation orientations were conceptualised as consisting of three facets, namely, acculturation demands (what migrants should do), perceptions (what migrants are perceived to want) and own goals (how participants want to deal with their own changing mainstream culture). Each of these three facets was assessed with the two dimensions culture maintenance and culture adoption. Results showed that all three kinds of contact had positive effects. Over time, mere contact changed other variables (it decreased negative emotions and realistic threat perceptions) than personal and extended contact (that decreased prejudice and discrimination intentions). Thus, it could be shown that desegregation leads to positive attitudinal effects and that the effects of mere contact are different from those of personal and extended contact.Vorurteile gegenüber und Diskriminierung von Migranten sind schwerwiegende Probleme unserer modernen, globalisierten Welt. In der vorliegenden Arbeit wurde untersucht, wie negative Einstellungen von Mitgliedern der Mehrheitsgesellschaft gegenüber Asylbewerbern mit Kontakterfahrungen, Bedrohungswahrnehmungen und Akkulturationsorientierungen zusammenhängen. Eine längsschnittliche Feldstudie mit zwei Meßzeitpunkten wurde mit den deutschen Einwohnern (N = 70) eines Wohngebietes durchgeführt, in dem eine Asylbewerberunterkunft eröffnet wurde. Direkt vor und sechs Monate nach der Eröffnung wurden die Einstellungen (d.h. Vorurteile, negative Emotionen und Diskriminierungsabsichten) und Kontakterfahrungen mit Fragebögen erhoben. Die Studie hat verschiedene theoretische Hintergründe. Erstens wurden Kontakterfahrungen analysiert. Verbesserungen der Einstellungen durch bloßen Kontakt (bloße Anwesenheit der Migranten), persönlichen Kontakt (eigene Kontakterfahrungen) und vermittelten Kontakt (Kenntnis von Kontakterfahrungen der Nachbarn) wurden verglichen. Zweitens wurden realistische und symbolische Bedrohungswahrnehmungen mit den Einstellungen verbunden. Einige Ansätze betrachten stabile Persönlichkeitseigenschaften wie Autoritarismus oder Vorurteile als kausale Ursache von Bedrohung. Andere Ansätze (zum Beispiel das Integrierte Bedrohungsmodell) sehen Bedrohungswahrnehmungen als Ursache von Vorurteilen. Diese konträren Kausalannahmen wurden geprüft. Drittens wurden Akkulturationsorientierungen mit Einstellungen und persönlichen Kontakterfahrungen verbunden. Dabei wurden drei Facetten differenziert: Akkulturationsforderungen (was Migranten tun sollten), -wahrnehmungen (Wahrnehmungen der Ziele der Migranten), sowie eigene -ziele (Veränderungen der deutschen Mehrheitskultur). Jede dieser Facetten wurde auf den Dimensionen Kulturerhaltung und -übernahme erfasst

A simple opto-fluidic switch detecting liquid filling in polymer-based microfluidic systems

A novel detection scheme for detection of liquid levels and bubbles in microfluidic systems, using the principle of total internal reflection (TIR) is presented. A laser beam impinges on the side walls of a channel which are inclined at 45deg. In an unfilled channel of such a "V-groove", TIR deflects the beam by 90deg into a simple light detector. Upon the presence of liquid, the refractive index in the channel changes, thus eliminating deflection by TIR. The detection principle is robust, requiring no calibration, and tolerating alignment errors of the laser larger than the width and depth of the microfluidic channels. The machining of the V-groves can seamlessly be integrated into common polymer microfabrication schemes such as injection molding