Cryptophagids from the Maltese Islands with description of a new species of Micrambe THOMSON (Coleoptera: Cryptophagidae)

The Cryptophagidae (Coleoptera) of the Maltese Islands are reviewed based on material of earlier records and recent collections. A total of twelve species are reported, of which Micrambe mediterranica OTERO & JOHNSON sp.n. is described from material collected in Malta, Greece and Jordan.peer-reviewe

Spatial interaction models applied to the design of retail trade areas

Intermetropolitan trade areas are geographical zones defined by consumer movements over space -retail flows- from their municipalities of residence towards a head town, to purchase special goods: clothing and footwear, furniture, food, etc. These market areas own an economic sense that do not have other more commonly used territorial divisions, such as towns, provinces or regions. Since 1992, the Lawrence R. Klein Institute -Autonoma University of Madrid-actualises the Spanish Retail Trade Atlas and determines regional trade areas and sub-areas, using spatial gravity models and survey. The authors' experience in this Project allows them to analyse the different procedures suggested for modelling the consumer store-choice process and from this, estimating the market share of a retail outlet or a town. Store choice models can be classified into two main groups. First, the descriptive-determinist approach includes a group of techniques that rely on observation or normative assumptions. It is well-known the procedure devised by Applebaum (1961) for constructing primary trade areas from customers spotted on a location map or the classical central place theory, based on the nearest-centre hypothesis. 'Reilly's law of retail gravitation' (1931) considers not only distance but also attractiveness of alternative shopping opportunities. Secondly, the explicative-stochastic approach uses information revealed by past behaviour to understand the dynamics of retail competition and how consumers choose among alternative shopping opportunities. Huff was the first to use a utility function and introduced the spatial interaction models to explain consumer behaviour. They argued that consumers rate alternatives on the basis of their evaluation of the total utility of the store and not merely on its location. Huff's model is a particular case of the discrete-choice models known as multinomial logit (McFadden, 1974). Both models satisfies the so-called 'Independece of Irrelevant Alternatives' (IIA) property, that is, the ratio of the probabilities of an individual selecting two alternatives is unaffected by the addition of a third alternative. While this may be reasonably representative of certain aspatial choice situations, it is very unlikely to occur in spatial choice because of the fixed locations of spatial alternatives. The competing destinations model, derived from purely spatial considerations, provides a way of overcoming some problems with the logit and nested logit models that arise from the transference of essentially aspatial theory to the spatial realm. This work focuses on market area delimitation models and presents the estimation process developed by the L.R. Klein Institute in determining intermetropolitan trade areas. It is also applied a competing destinations model to the trade area of Madrid, a very peculiar one because of its magnitude and the important shopping concentration around the capital. Finally, we want to highlight the main applications derived from the knowledge and actualisation of the consumer retail flows. These applications take into account not only retailing but also another economic activities relating with market attraction areas.

Assessment of joint inventory replenishment: a cooperative games approach

This research deals with the design of a logistics strategy with a collaborative approach between non-competing companies, who through joint coordination of the replenishment of their inventories reduce their costs thanks to the exploitation of economies of scale. The collaboration scope includes sharing logistic resources with limited capacities; transport units, warehouses, and management processes. These elements conform a novel extension of the Joint Replenishment Problem (JRP) named the Schochastic Collaborative Joint replenishment Problem (S-CJRP). The introduction of this model helps to increase practical elements into the inventory replenishment problem and to assess to what extent collaboration in inventory replenishment and logistics resources sharing might reduce the inventory costs. Overall, results showed that the proposed model could be a viable alternative to reduce logistics costs and demonstrated how the model can be a financially preferred alternative than individual investments to leverage resources capacity expansions. Furthermore, for a practical instance, the work shows the potential of JRP models to help decision-makers to better understand the impacts of fleet renewal and inventory replenishment decisions over the cost and CO2 emissions.DoctoradoDoctor en Ingeniería Industria

Unions and Job Queuing in Mexico's Maquiladoras

The U.S.-Mexico border region has experienced substantial economic growth over the last two decades; nonetheless, employment and wage growth has been uneven across the border cities with a high maquiladora presence. We hypothesize that these growth differences can be traced to relative labor union power. Using microdata from the 1998 National Urban Employment Survey, we find evidence of job queuing in Mexico’s maquiladoras. Queuing seems to be stronger in cities with powerful labor unions such as Matamoros and Nuevo Laredo, but it is weaker in cities where union strength is minimal such as Ciudad Juárez and Tijuana.Union

Más allá de las ideas previas como dificultades de aprendizaje : las pautas de pensamiento, las concepciones epistemológicas y las estrategias metacognitivas de los alumnos de ciencias

In this article we try to go beyond students misconceptions as the only explanation for difficulties in the learning of sciences. We review the main components of a kind of «cognitive conspiration» against the work of science teachers: the preconceptions of students, their patterns of thinking and reasoning, their epistemological beliefs and their metacognitive strategies. Usually, research in science education has focused on the two first elements, although, in recent years, researchers have started to focus on the two last factors that are main obstacles for science learning and are responsible for the failure of many new approaches in science teaching

Sensitivity of a distributed temperature-radiation index melt model based on AWS observations and surface energy balance fluxes, Hurd Peninsula glaciers, Livingston Island, Antarctica

We use an automatic weather station and surface mass balance dataset spanning four melt seasons collected on Hurd Peninsula Glaciers, South Shetland Islands, to investigate the point surface energy balance, to determine the absolute and relative contribution of the various energy fluxes acting on the glacier surface and to estimate the sensitivity of melt to ambient temperature changes. Long-wave incoming radiation is the main energy source for melt, while short-wave radiation is the most important flux controlling the variation of both seasonal and daily mean surface energy balance. Short-wave and long-wave radiation fluxes do, in general, balance each other, resulting in a high correspondence between daily mean net radiation flux and available melt energy flux. We calibrate a distributed melt model driven by air temperature and an expression for the incoming short-wave radiation. The model is calibrated with the data from one of the melt seasons and validated with the data of the three remaining seasons. The model results deviate at most 140 mm w.e. from the corresponding observations using the glaciological method. The model is very sensitive to changes in ambient temperature: a 0.5 ◦ C increase results in 56 % higher melt rates