Natural Gauge and Gravitational Coupling Unification and the Superpartner Masses

The possibility to achieve unification at the string scale in the context of the simplest supersymmetric grand unified theory is investigated. We find conservative upper bounds on the superpartner masses consistent with the unification of gauge and gravitational couplings, M_{\tilde G} < 5 TeV and M_{\tilde f} < 3 \times 10^7 GeV, for the superparticles with spin one-half and zero, respectively. These bounds hint towards the possibility that this supersymmetric scenario could be tested at future colliders, and in particular, at the forthcoming LHC.Comment: 8 pages, 4 figures, version accepted in Physics Letters

Two and three electrons in a quantum dot: 1/|J| - expansion

We consider systems of two and three electrons in a two-dimensional parabolic quantum dot. A magnetic field is applied perpendicularly to the electron plane of motion. We show that the energy levels corresponding to states with high angular momentum, J, and a low number of vibrational quanta may be systematically computed as power series in 1/|J|. These states are relevant in the high-B limit.Comment: LaTeX, 15 pages,6 postscript figure

Mixture optimization of an alkali-activated steel slag to maximize binder strength using optimal design of experiments

The diversity of precursors suitable for alkali activation demands a flexible methodology to study the properties of alkali-activated binders. Optimal design of experiments (ODOE) [1] allows a systematic and efficient exploration of effects and interactions among mix components and processing conditions, a situation commonly found during proportioning studies. Moreover, the ODOE algorithms provide sets of experiments of an optimized size that consider all the factors studied at the same time, a key feature to detect absolute maximums (or minimums) of a response. In this case, the strength-optimized proportioning for basic-oxygen-furnace (BOF) slag specimens activated with NaOH solutions was determined. The impact of solution molarity ranging from 0M (only water) to 0.5M and the additions of gypsum (2 to 6 wt%), Portland cement (0 to 10 wt%) and 0.2 wt% of a commercial plasticizer (polycarboxylate-based dispersant) were mapped. Proportions tested were selected running ODOE software using an I-optimality criteria algorithm, which minimizes the average variance of model prediction. A response surface model (RSM) for 28-day strength was defined. Paste and mortar specimens were produced with the predicted proportioning of highest strength and its binding matrix was characterized and compared with low-strength samples using X-ray diffraction (XRD), secondary electron microscopy (SEM) and infrared spectrometry (FTIR). The results obtained confirm that the methodology generates a model able to predict mechanical response, detecting general trends, high impact factors and interactions. More important, the optimal experimental design can be used to effectively study changes in the binding matrices and link them to the binder’s mechanical performance. Please click Additional Files below to see the full abstract

Model checking GSM-based multi-agent systems

Business artifacts are a growing topic in service oriented computing. Artifact systems include both data and process descriptions at interface level thereby providing more sophisticated and powerful service inter-operation capabilities. The Guard-Stage-Milestone (GSM) language provides a novel framework for specifying artifact systems that features declarative descriptions of the intended behaviour without requiring an explicit specification of the control flow. While much of the research is focused on the design, deployment and maintenance of GSM programs, the verification of this formalism has received less attention. This thesis aims to contribute to the topic. We put forward a holistic methodology for the practical verification of GSM-based multi-agent systems via model checking. The formal verification faces several challenges: the declarative nature of GSM programs; the mechanisms for data hiding and access control; and the infinite state spaces inherent in the underlying data. We address them in stages. First, we develop a symbolic representation of GSM programs, which makes them amenable to model checking. We then extend GSM to multi-agent systems and map it into a variant of artifact-centric multi-agent systems (AC-MAS), a paradigm based on interpreted systems. This allows us to reason about the knowledge the agents have about the artifact system. Lastly, we investigate predicate abstraction as a key technique to overcome the difficulty of verifying infinite state spaces. We present a technique that lifts 3-valued abstraction to epistemic logic and makes GSM programs amenable to model checking against specifications written in a quantified version of temporal-epistemic logic. The theory serves as a basis for developing a symbolic model checker that implements SMT-based, 3-valued abstraction for GSM-based multi-agent systems. The feasibility of the implementation is demonstrated by verifying GSM programs for concrete applications from the service community.Open Acces

Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems

Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities

Peculiarities of phases of the WMAP quadrupole

We present the analysis on the quadrupole phases of the Internal Linear Combination map, ILC(I) and (III) derived by the WMAP team (1 and 3-year data release). This approach allows us to see the global trend of non-Gaussianity of the quadrupoles for the ILC(III) map through phase correlations with the foregrounds. Significant phase correlations is found in between the ILC(III) quadrupole and the WMAP foregrounds phases for K-W band: the phases of the ILC(III) quadrupole xi_{2,1}, xi_{2,2} and those of the foregrounds at K-W bands Phi_{2,1}, Phi_{2,2} display significant symmetry: xi_{2,1}+Phi_{2,1} ~= xi_{2,2}+Phi_{2,2}, which is a strong indication that the morphology of the ILC(III) quadrupole is mere reflection of that the foreground quadrupole through coupling. To clarify this issue we exploit the symmetry of the CMB power, which is invariant under permutation of the index m=12. By simple rotation of the ILC(III) phases with the same angle we reach the phases of foreground quadrupole. We discuss possible sources of phase correlation and come to the conclusion that the phases of the ILC(III) quadrupole reflect most likely systematic effects such as changing of the gain factor for the 3-year data release with respect to the 1-year, rather than manifestation of the primordial non-Gaussianity.Comment: 8 pages, 15 page