On the isomorphism problem of concept algebras

Weakly dicomplemented lattices are bounded lattices equipped with two unary operations to encode a negation on {\it concepts}. They have been introduced to capture the equational theory of concept algebras \cite{Wi00}. They generalize Boolean algebras. Concept algebras are concept lattices, thus complete lattices, with a weak negation and a weak opposition. A special case of the representation problem for weakly dicomplemented lattices, posed in \cite{Kw04}, is whether complete {\wdl}s are isomorphic to concept algebras. In this contribution we give a negative answer to this question (Theorem \ref{T:main}). We also provide a new proof of a well known result due to M.H. Stone \cite{St36}, saying that {\em each Boolean algebra is a field of sets} (Corollary \ref{C:Stone}). Before these, we prove that the boundedness condition on the initial definition of {\wdl}s (Definition \ref{D:wdl}) is superfluous (Theorem \ref{T:wcl}, see also \cite{Kw09}).Comment: 15 page

Commercio elettronico per la dinamica delle catene agro-alimentari internazionali: un’analisi del potenziale [E-commerce for the dynamics of international agri-food chains: an adoption potential analysis]

Business-to-business (B2B) e-commerce is an innovative use of information and communication technologies and refers to the exchange of goods and related information between companies supported by Internet-based tools such as electronic marketplaces (also called electronic trade platforms) or online shops. It provides opportunities for cost-efficiency in supply chain management processes and access to new markets. With regard to the food sector with its chain levels input – agriculture – industry – retail – consumer, B2B e-commerce would take place in the exchange of food products between all levels except retail to consumer (business-to-consumer e-commerce). It is evident and widely known that B2B e-commerce brings key advantages and potentials for European consumers and the European food sector: - The affordability of high quality, traceable food for European consumers is supported as the innovation potentials from e-commerce technologies for cost-efficient processes along the food chain. The healthy choice of quality food will become the easy and affordable choice for European consumers. - The competitiveness of the European food sector with the majority of SMEs increases as B2B e-commerce technologies support cost-efficient transaction processes in food supply chains. In recent years, the availability of sophisticated B2B e-commerce technology has improved tremendously. The “European e-Business Market Watch” initiative from the Directorate-General Enterprise and Industry from the European Commission has shown that only large multinationals exploit the potentials of B2B e-commerce in the food sector for their supply chain management with their business partners. SMEs however, which create the majority of turn over in the European food sector and therefore create jobs and welfare in Europe, are reluctant to take up existing B2B e-commerce technologies into their food supply of selling. The crucial barrier to adoption is that trust between companies is not mediated appropriately by existing e-commerce technology. Currently, the barrier for food sector SMEs towards B2B e-commerce come from - the difficulty to examine the quality and safety of food products. This refers to all kinds of transactions in the food sector, whether supported by e-commerce or not. However, when it comes to e-commerce, the difficulty of physical product examination plays a much larger role as physical product inspection is not possible; - the (perceived) risk of performing a transaction via e-commerce. This includes concerns regarding secure transfer of data, or the possibly unknown transaction partner. Elements for the generation of trust between companies in the food chain and therefore of trustworthy B2B e-commerce environments for the food sector include guaranties regarding food quality, multimedia food product presentations to signal their quality, secure e-commerce technology infrastructures, third-party quality signs to be provided. As trust is highly subjective and depends on culture, food chains in different European countries with a different cultural background require different combinations of trust generating elements regarding the quality and safety of food. Different food chain scenarios with their transaction processes and risks regarding food quality and food safety and related trust elements need to be analysed and differences in trust in different European food chains need to be considered. It is the objective of this paper to identify food chains with trans-European cross-border exchange of food and international food chains in order to analyse the transaction processes and typical risks regarding food quality and food safety. The analysis focuses on trans-European cross-border and international food chains with their chain levels (e.g. production to wholesale trade, wholesale trade to industry, or wholesale trade to retail). In particular, it regards the food categories meat, grains, fresh vegetables, and fresh fruits and the particular risks regarding food quality and safety along the chains.e-commerce, B2B transactions, agri-food trade

Synthesis of non-linear protein dimers through a genetically encoded thiol-ene reaction

Site-specific incorporation of bioorthogonal unnatural amino acids into proteins provides a useful tool for the installation of specific functionalities that will allow for the labeling of proteins with virtually any probe. We demonstrate the genetic encoding of a set of alkene lysines using the orthogonal PylRS/PylTCUA pair in Escherichia coli. The installed double bond functionality was then applied in a photoinitiated thiol-ene reaction of the protein with a fluorescent thiol-bearing probe, as well as a cysteine residue of a second protein, showing the applicability of this approach in the formation of heterogeneous non-linear fused proteins. © 2014 Torres-Kolbus et al

The M/L ratio of massive young clusters

We point out a strong time-evolution of the mass-to-light conversion factor \eta commonly used to estimate masses of dense star clusters from observed cluster radii and stellar velocity dispersions. We use a gas-dynamical model coupled with the Cambridge stellar evolution tracks to compute line-of-sight velocity dispersions and half-light radii weighted by the luminosity. Stars at birth are assumed to follow the Salpeter mass function in the range [0.15--17 M_\sun]. We find that $\eta$, and hence the estimated cluster mass, increases by factors as large as 3 over time-scales of 20 million years. Increasing the upper mass limit to 50 M_\sun leads to a sharp rise of similar amplitude but in as little as 10 million years. Fitting truncated isothermal (Michie-King) models to the projected light profile leads to over-estimates of the concentration par ameter c of $\delta c\approx 0.3$ compared to the same functional fit applied to the proj ected mass density.Comment: Draft version of an ApJ lette

A New High-intensity, Low-momentum Muon Beam for the Generation of Low-energy Muons at PSI

At the Paul Scherrer Institute (PSI, Villigen, Switzerland) a new high-intensity muon beam line with momentum p < 40MeV/c is currently being commissioned. The beam line is especially designed to serve the needs of the low-energy, polarized positive muon source (LE-μ+) and LE-μ SR spectrometer at PSI. The beam line replaces the existing μ E4 muon decay channel. A large acceptance is accomplished by installing two solenoidal magnetic lenses close to the muon production target E that is hit by the 590-MeV PSI proton beam. The muons are then transported by standard large aperture quadrupoles and bending magnets to the experiment. Several slit systems and an electrostatic separator allow the control of beam shape, momentum spread, and to reduce the background due to beam positrons or electrons. Particle intensities of up to 3.5 × 108 μ+/s and 107 μ−/s are expected at 28MeV/c beam momentum and 1.8mA proton beam current. This will translate into a LE-μ+ rate of 7,000/s being available at the LE-μ SR spectrometer, thus achieving μ+ fluxes, that are comparable to standard μ SR facilitie

Measurement of the Fermi Constant by FAST

An initial measurement of the lifetime of the positive muon to a precision of 16 parts per million (ppm) has been performed with the FAST detector at the Paul Scherrer Institute. The result is tau_mu = 2.197083 (32) (15) microsec, where the first error is statistical and the second is systematic. The muon lifetime determines the Fermi constant, G_F = 1.166353 (9) x 10^-5 GeV^-2 (8 ppm).Comment: 15 pages, 6 figure

AsylLeben in Deutschland: Biografische Annäherungen

Leben im Asyl bedeutet eine oft jahrelange Zeitspanne der Ungewissheit, eine Existenz in einem fragilen Zwischenraum, die häufig nur schwer zu bewältigen ist. Wie blicken Betroffene auf diese Phase und ihren Weg aus der Heimat in ein neues Land und Dasein? Diesen auf das erlebende Subjekt ausgerichteten Fragen sind Studierende des Kölner Instituts für Ethnologie im Rahmen eines Hauptseminars zur Biografischen Methode nachgegangen. Der vorliegende Beitrag bildet zum einen in biografischen Kurzporträts die Perspektiven der Personen ab, mit denen lebensgeschichtliche Gespräche zu ihrem "Asyl-Er-Leben" in Deutschland geführt wurden, zum anderen zeichnet er die Erfahrungen mit den Besonderheiten biografischer Interviews, ihrer Auswertung und Repräsentation nach

Perceived risks in cross-border transactions in agri-food chains

Nowadays, agri-food chains are more global than ever and are characterized by increased imports and exports and global sourcing of products, resulting in increased cross-border transaction risks. The objective of this paper is to identify the typical risks regarding agri-food supply chains involved in cross-border transactions and to assess their importance as perceived by agri-food managers. The analysis takes into consideration four different agrifood value chains (meat, grain, olive oil, fresh vegetables and fruits). Following an explorative approach and a qualitative technique, a series of face to face in-depth interviews was conducted. Results indicate that risk perception may be quite different across countries, value chains, tiers of the supply chain, as well as across respondents. The prevalence of Market dynamics risks was pointed out in most of the interviews, yielding the impression that many operators identify the market as the most difficult environment. Differences in risk perception between fresh produce (fruit/vegetables and meat) and processed food chains (grain and olive oil) are probably interrelated to the different degree of integration within these supply chains, the different level of standardization achieved and the different causes of risks that are inherent to the nature of the product.Perceived Risks, Cross-Border Transactions, Agri-Food Chains, Risk and Uncertainty,

Estimation of the Thermodynamic Limit of Overheating for Bulk Water from Interfacial Properties

The limit of overheating or expanding is an important property of liquids, which is relevant for the design and safety assessment of processes involving pressurized liquids. In this work, the thermodynamic stability limit – the so-called spinodal – of water is calculated by molecular dynamics computer simulation, using the molecular potential model of Baranyai and Kiss. The spinodal pressure is obtained from the maximal tangential pressure within a liquid‒vapor interface layer. The results are compared to predictions of various equations of states. Based on these comparisons, a set of equations of state is identified which gives reliable results in the metastable (overheated or expanded) liquid region of water down to −55 MPa