A sound and complete reified temporal logic

There are mainly two known approaches to the representation of temporal information in Computer Science: modal logic approaches (including tense logics and hybrid temporal logics) and predicate logic approaches (including temporal argument methods and reified temporal logics). On one hand, while tense logics, hybrid temporal logics and temporal argument methods enjoy formal theoretical foundations, their expressiveness has been criticised as not power enough for representing general temporal knowledge; on the other hand, although current reified temporal logics provide greater expressive power, most of them lack of complete and sound axiomatic theories. In this paper, we propose a new reified temporal logic with a clear syntax and semantics in terms of a sound and complete axiomatic formalism which retains all the expressive power of the approach of temporal reification.

The completeness and soundness of temporal theories

Generally speaking, the term temporal logic refers to any system of rules and symbolism for representing and reasoning about propositions qualified in terms of time. In computer science, particularly in the domain of Artificial Intelligence, there are mainly two known approaches to the representation of temporal information: modal logic approaches including tense logic and hybrid temporal logic, and predicate logic approaches including temporal arguement method and reified temporal logic. On one hand, while tense logic, hybrid temporal logic and temporal argument method enjoy formal theoretical foundations, their expressiveness has been criticised as not power enough for representing general temporal knowledge; on the other hand, although reified temporal logic provides greater expressive power, most of the current systems following the temporal reification lack of complete and sound axiomatic theories. With there observations in mind, a new reified temporal logic with clear syntax and semantics in terms of a sound and complete axiomatic formalism is introduced in this paper, which retains all the expressive power of temporal reification.

Mode shape expansion using perturbed force vector approach

A new technique for mode shape expansion in structural dynamic applications is presented based on the perturbed force vector approach. The proposed technique can directly adopt the measured incomplete modal data and include the effect of the perturbation between the analytical and test models. The results show that the proposed technique can provide very accurate expanded mode shapes, especially in cases when significant modelling error exists in the analytical model and limited measurements are available.

Oceanographic responses to climate in the northwest Atlantic

Situated in an oceanographic transition zone, the Gulf of Maine/Western Scotian Shelf (GOM/WSS) region of the Northwest Atlantic is especially susceptible to changes in the climate system. Recent studies have shown that a coupled slope water system (CSWS) operates in the Northwest Atlantic and responds in a similar manner to climatic forcing over a broad range of time scales. These studies further suggest that it may be possible to associate different modes of the CSWS with the different phases of the North Atlantic Oscillation (NAO). Results from recent GLOBEC field studies in the Northwest Atlantic provide strong evidence linking physical responses of the CSWS to basin-scale forcing associated with the NAO. By placing these results in the context of time-series data collected from the GOM/WSS over the past half century, we show that we show that: (i) the region’s shelf ecosystems respond both physically and biologically to modal shifts in the CSWS; (ii) the CSWS mediates the effects on these ecosystems of basin-scale climatic forcing associated with the NAO and (iii) certain planktonic species can be good indicators of the CSWS’s modal state on inter-annual to interdecadal time scales.

The influence of phytoplankton productivity, temperature and environmental stability on the control of copepod diversity in the North East Atlantic

The patterns of copepod species richness (S) and their relationship with phytoplankton productivity, temperature and environmental stability were investigated at climatological, seasonal and year-to-year time scales as well as scales along latitudinal and oceanic–neritic gradients using monthly time series of the Continuous Plankton Recorder (CPR) Survey collected in the North East Atlantic between 1958 and 2006. Time series analyses confirmed previously described geographic patterns. Equatorward and towards neritic environments, the climatological average of S increases and the variance explained by the seasonal cycle decreases. The bi-modal character of seasonality increases equatorward and the timing of the seasonal cycle takes place progressive earlier equatorward and towards neritic environments. In the long-term, the climatological average of S decreased significantly (p < 0.001) between 1958 and 2006 in the Bay of Biscay and North Iberian shelf at a rate of ca. 0.04 year−1, and increased at the same rate between 1991 and 2006 in the northernmost oceanic location. The climatological averages of S correlate positively with those of the index of seasonality of phytoplankton productivity (ratio between the minimum and maximum monthly values of surface chlorophyll) and sea surface temperature, and negatively with those of the proxy for environmental stability (monthly frequency of occurrence of daily averaged wind speed exceeding 10 m s−1). The seasonal cycles of S and phytoplankton productivity (surface chlorophyll as proxy) exhibit similar features in terms of shape, timing and explained variance, but the relationship between the climatological averages of both variables is non-significant. From year-to-year, the annual averages of S correlate negatively with those of phytoplankton productivity and positively with those of sea surface temperature along the latitudinal gradient, and negatively with those of environmental stability along the oceanic–neritic gradient. The annual anomalies of S (i.e. factoring out geographic variation) show a unimodal relationship with those of sea surface temperature and environmental stability, with S peaking at intermediate values of the anomalies of these variables. The results evidence the role of seasonality of phytoplankton productivity on the control of copepod species richness at seasonal and climatological scales, giving support to the species richness–productivity hypothesis. Although sea surface temperature (SST) is indeed a good predictor of richness along the latitudinal gradient, it is unable to predict the increase of richness form oceanic to neritic environments, thus lessening the generality of the species richness–energy hypothesis. Meteo-hydrographic disturbances (i.e. SST and wind speed anomalies as proxies), presumably through its role on mixed layer depth dynamics and turbulence and hence productivity, maximise local diversity when occurring at intermediate frequency and or intensity, thus providing support to the intermediate disturbance hypothesis on the control of copepod diversity.

The first time: young people and sex in Northern Ireland.

The sexual health of people, particularly young people, in Northern Ireland is currently poor. Yet there has been little research conducted on sexual attitudes and lifestyles. This paper is based on data from the first ever major research project in this field in Northern Ireland. Using quantitative and qualitative methods, it targeted young people aged 14-25. A combination of a self-administered survey questionnaire, focus group discussions and one-to-one interviews was found to be most suitable for the collection of sensitive data on sexuality in a country where the social and moral climate had previously prevented studies of this nature. Information was collected on sexual attitudes and behaviour generally. This paper focuses on one crucial issue: the age of first sexual encounter. It explores the attitudes of young people to that experience and the use of contraception. Many of the findings match those of similar large-scale surveys in England and Wales, including the modal age of first sexual encounter and the influence of peer pressure on decision-making about first sex. There were significant gender differences in both behaviour and attitudes. It is hoped that the research results will influence future education and health policy, which has all too often been based on ignorance.

Micromachined 300GHz high Q resonant slot frequency selective surface filter

The design of a low loss quasi-optical beam splitter which is required to provide efficient diplexing of the bands 316.5-325.5 GHz and 349.5-358.5 GHz is presented. To minimise the filter insertion loss, the chosen architecture is a three-layer freestanding array of dipole slot elements. Floquet modal analysis and finite element method computer models are used to establish the geometry of the periodic structure and to predict its spectral response. Two different micromachining approaches have been employed to fabricate close packed arrays of 460 mm long elements in the screens that form the basic building block of the 30mm diameter multilayer frequency selective surface. Comparisons between simulated and measured transmission coefficients for the individual dichroic surfaces are used to determine the accuracy of the computer models and to confirm the suitability of the fabrication methods.

Perspectives for quantum state engineering via high nonlinearity in a double-EIT regime

We analyse the possibilities for quantum state engineering offered by a model for Kerr-type nonlinearity enhanced by electromagnetically induced transparency (EIT), which was recently proposed by Petrosyan and Kurizki [2002, Phys. Rev. A, 65, 33833]. We go beyond the semiclassical treatment and derive a quantum version of the model with both a full Hamiltonian approach and an analysis in terms of dressed states. The preparation of an entangled coherent state via a cross-phase modulation effect is demonstrated. We briefly show that the violation of locality for such an entangled coherent state is robust against low detection efficiency. Finally, we investigate the possibility of a bi-chromatic photon blockade realized via the interaction of a low density beam of atoms with a bi-modal electromagnetic cavity which is externally driven. We show the effectiveness of the blockade effect even when more than a single atom is inside the cavity. The possibility to control two different cavity modes allows some insights into the generation of an entangled state of cavity modes.

De la cooperativa agroalimentaria a la "learning netchain". Hacia un planteamiento teorico interorganizativo e interpersonal

Se propone un planteamiento teórico/conceptual para determinar si las relaciones interorganizativas e interpersonales de la netchain de las cooperativas agroalimentarias evolucionan hacia una learning netchain. Las propuestas del trabajo muestran que el mayor grado de asociacionismo y la mayor cooperación/colaboración vertical a lo largo de la cadena están positivamente relacionados con la posición horizontal de la empresa focal más cercana del consumidor final. Esto requiere una planificación y una resolución de problemas de manera conjunta, lo que está positivamente relacionado con el mayor flujo y diversidad de la información/conocimiento obtenido y diseminado a lo largo de la netchain. Al mismo tiempo se necesita desarrollar un contexto social en el que fluya la información/conocimiento y las nuevas ideas de manera informal y esto se logra con redes personales y, principalmente, profesionales y con redes internas y, principalmente, externas. Todo esto permitirá una mayor satisfacción de los socios de la cooperativa agroalimentaria y de sus distribuidores y una mayor intensidad en I+D, convirtiéndose la netchain de la cooperativa agroalimentaria, así, en una learning netchain.

Periodic FDTD analysis of a 2-D leaky-wave planar antenna based on dipole frequency selective surfaces

A periodic finite-difference time-domain (FDTD) analysis is presented and applied for the first time in the study of a two-dimensional (2-D) leaky-wave planar antenna based on dipole frequency selective surfaces (FSSs). First, the effect of certain aspects of the FDTD modeling in the modal analysis of complex waves is studied in detail. Then, the FDTD model is used for the dispersion analysis of the antenna of interest. The calculated values of the leaky-wave attenuation constants suggest that, for an antenna of this type and moderate length, a significant amount of power reaches the edges of the antenna, and thus diffraction can play an important role. To test the validity of our dispersion analysis, measured radiation patterns of a fabricated prototype are presented and compared with those predicted by a leaky-wave approach based on the periodic FDTD results.

Periodically loaded dipole array supporting left-handed propagation

Periodically loaded dipole arrays printed on grounded dielectric substrate are shown to exhibit left-handed propagation properties. In an equivalent transmission line representation, lefthandedness emerges due to the excess series capacitance and shunt inductance. Based on this concept, the authors study the distribution of the modal fields and the variation of series capacitance and shunt inductance as the dipoles are loaded with stubs. Full wave dispersion curves that show the gradual transition from a right-handed to a left-handed medium upon periodically loading the dipoles with stubs are presented. An equivalent circuit is derived that matches to a very good extent the full wave result. The cell dimensions are a small fraction of the wavelength (),15), so the structure can be considered as an equivalent homogeneous surface. The structure is simple, readily scalable to higher frequencies and compatible with low-cost fabrication techniques.

Efficient modeling of novel uniplanar left-handed metamaterials

This paper presents an efficient. modeling technique for the derivation of the dispersion characteristics of novel uniplanar metallodielectric periodic structures. The analysis is based on the method of moments and an interpolation scheme, which significantly accelerates the computations. Triangular basis functions are used that allow for modeling of arbitrary shaped metallic elements. Based on this method, novel uniplanar left-handed (LH) metamaterials are proposed. Variations of the split rectangular-loop element printed on grounded dielectric substrate are demonstrated to possess LH propagation properties. Full-wave dispersion curves are presented. Based on the dual transmission-line concept, we study the distribution of the modal fields And the variation of series capacitance and shunt inductance for all the proposed elements. A verification of the left-handedness is presented by means of full-wave simulation of finite uniplanar arrays using commercial software (HFSS). The cell dimensions are a small fraction of the wavelength (approximately lambda/24) so that the structures can he considered as a homogeneous effective medium. The structures are simple, readily scalable to higher frequencies, and compatible with low-cost fabrication techniques.

Uniplanar left-handed artificial metamaterials

Planar periodic arrays of metallic elements printed on grounded dielectric substrates are presented to exhibit left-handed properties for surface wave propagation. The proposed structures dispense with the need for grounding vias and ease the implementation of uniplanar left-handed metamaterials at higher frequencies. A transmission line description is used for the initial design and interpretation of the left-handed property. A thorough study based on full wave simulations is carried out with regards to the effect of the element geometrical characteristics and the array periodicity to the properties of the artificial material. Dispersion curves are presented and studied. The distribution of the modal fields in the unit cell is also studied in order to provide an explanation of the material properties. The scalability of the proposed structures to infrared frequencies is demonstrated.

Efficient modelling technique for fractal electromagnetic band-gap arrays

An efficient modelling technique is proposed for the analysis of a fractal-element electromagnetic band-gap array. The modelling is based on a method of moments modal analysis in conjunction with an interpolation scheme, which significantly accelerates the computations. The plane-wave and the surface-wave responses of the structure have been studied by means of transmission coefficients and dispersion diagrams. The multiband properties and the compactness of the proposed structure are presented. The technique is general and can be applied to arbitrary-shaped element geometries.

Working with a child Exposed to Community and Domestic violence in Northern Ireland: An Illustrated Case Example.

The focus of this paper is on the author’s multi-modal therapeutic practice with a 7-year-old boy referred to the Family Trauma Centre, following paramilitary assaults on his father. The work also addresses the boy’s experience of domestic violence. The work is contextualised in terms of the ‘Peace Process’ in Northern Ireland, including the establishment of the Family Trauma Centre as a response to the needs of victims of the Troubles. A rationale for working with children using a multi-modal approach is presented.