Antecedents of construction project coalitions: a study of the Spanish construction industry

Research into the formation of alliances, relevant in the field of strategic management and especially, in the construction industry, is often explained in terms of interdependency and complementarities (exogenous factors). In contrast, the influence of a firm’s social relations networks (endogenous factors) has hardly been studied at all. Thus, a model is needed that includes both exogenous and endogenous factors as antecedents to the formation of strategic alliances in the construction industry. Cooperation in the construction sector is especially frequent, above all in public works programmes, as their scale requires coalitions of different‐sized firms. Accordingly, to explore how both exogenous and endogenous factors influence the formation of alliances, a social network analytical method—Multiple Regression Quadratic Assignment Procedure (MRQAP)—was applied to cooperative project coalitions in the Spanish public works construction sector from 2001–2007. Empirical findings confirm that construction companies form coalitions, principally on the basis of past alliances. Membership of business associations and groups is also a key factor, though the influence of geographic proximity is the most debatable result. In the construction industry, the formation of alliances is conditioned, among other factors, by previous social and economic relations that can generate the necessary information and trust for the selection of whichever partner is considered the most suitable for the development of the joint project.     

Spread or backwash: The impact on population dynamics and business performance of a new road in a rural county of Galicia (Spain)

The natural experiment provided by the opening of a section that completed the A8 motorway in Mariña de Lugo, a rural area in Galicia (Spain), offers an opportunity to identify whether spread or backwash effects in economic activity are observed. The new section directly affects only a small strip of the territory—where the transition from the inland rural areas to the more dynamic coastal area takes place. This allows us to test a separate dual inner-coastal socio-economic performance after the opening of the new road—an analysis that has rarely been performed for rural areas in developed countries. We study the impact over population growth, employment and business financial results, using the differences-in-differences approach. The results we obtain are consistent with the spread hypothesis for the nearest municipality to the new road section, while the spread effects did not disseminate to the neighbouring municipalities. These global results hide a different performance at the sector level, positive for transport and manufacturing companies, and negative for retail firms and hospitality.     

Continuous-Flow UV Liquid Food Pasteurization: Engineering Aspects

Ultraviolet (UV)-C treatments are a promising technology for liquid food pasteurization as an alternative to heat treatments. However, the design of efficient UV reactors to reduce pertinent microorganisms and comply with current food safety goals is still an engineering challenge due to the low penetration depth of UV light in liquid foods with high UV absorbance and suspended particles, and the variations in the residence time of the product in the UV reactors. This review focuses on physical aspects of UV radiation related to the essential product and processing parameters for the design of UV reactors. The UV equipment available for liquid food processing is described and the main drawbacks and advantages are discussed.     

Mass Transfer Modeling During Osmotic Dehydration of Hexahedral Pineapple Slices in Limited Volume Solutions

The study of mass transfer during osmotic dehydration process in limited volume solutions was carried out to evaluate the diffusion coefficients of sucrose and water in the osmotic treatment of hexahedral pineapple slices. The experimental osmotic dehydration kinetics for pineapple slices of two different sizes were conducted at 25 °C using a 1:1 solution to fruit weight ratio. The analytical solution of a 3D mass transfer model considering a limited volume of osmotic solution (i.e., an osmotic media of variable solute concentration) was used for describing the mass transfer in osmotic dehydration of pineapple slices. This model was fitted to the experimental kinetics by means of nonlinear regression to obtain the diffusion coefficients. Additionally, the diffusion coefficients were evaluated considering an infinite volume of osmotic solution (i.e., an osmotic media of constant solute concentration). Results showed that the proposed model may be fitted accurately to the experimental osmotic dehydration kinetics and allows the estimation of diffusion coefficients when solute concentration in the osmotic media varies along the process.     

The effect of environmental conditions on nutritional quality of cherry tomato fruits: evaluation of two experimental Mediterranean greenhouses

BACKGROUND: The aim of this study was to examine how different environmental factors (temperature, solar radiation, and vapour‐pressure deficit [VPD]) influenced nutritional quality and flavour of cherry tomato fruits (Solanum lycopersicum L. cv. Naomi) grown in two types of experimental Mediterranean greenhouses: parral (low technology) and multispan (high technology). RESULTS: Fruits were sampled three times during 3 years (2004, 2005 and 2006): at the beginning, middle and end of the fruit production period. Values for temperature, solar radiation, and VPD peaked in the third sampling in both greenhouses; values were higher in the parral‐type greenhouse, triggering abiotic stress. This stress reduced the accumulation of lycopene and essential elements, augmenting the phytonutrient content and the antioxidant capacity of tomatoes. During the third sampling, sugars were increased while organic acid content diminished, producing tomatoes with a sweeter‐milder flavour. The parral greenhouse produced tomatoes with higher phenolic compounds and ascorbic acid contents, together with a greater antioxidant capacity, without showing differences in flavour parameters. CONCLUSION: The higher phytonutrients content and antioxidant activity during the environmental stress, more pronounced in parral than multispan greenhouse, together with the sweeter‐milder flavour, conferred a notable nutritional benefit, which considerably improved the nutritional and organoleptic quality of these tomatoes. Copyright © 2010 Society of Chemical Industry     

Tannase activity by lactic acid bacteria isolated from grape must and wine

We examined a range of oenological lactic acid bacteria species and reference strains for their potential to degrade tannins. Bacterial tannase activity was checked by a spectrophotometric and a visual reading method. None of the strains belonging to the oenological species of the genus Lactobacillus, Leuconostoc, Oenococcus or Pediococcus were tannase producers, with the exception of Lactobacillus plantarum. All the L. plantarum strains analyzed were positive for tannase activity and their identities were reconfirmed by L. plantarum PCR-specific assay or by sequencing the 16S rDNA. Tannase activity could be considered an important criterion for the selection of malolactic starter cultures since it might confer advantages in the winemaking process by reducing astringency and haze in wine.     

Estimation of soil water repellency of different particle size fractions in relation with carbon content by different methods

The water repellency of soils with different texture under different types of plant cover was determined by applying the WDPT and MED methods to both whole samples and the following size fractions: 2-1, 1-0.5, 0.5-0.25, 0.25-0.05 and <0.05 mm. Based on the results, the soils under maize crop and grassland, which were mostly wettable in the whole samples, exhibited water repellency in the finest fraction (<0.05 mm) as a result of its higher organic carbon content. On the other hand, all fractions in the forest soils, which were extremely water repellent, contributed to the overall repellency; in any case, the MED test revealed that the finest fraction was strongly repellent in the forest soils as well.     

Model selection, identification and validation in anaerobic digestion: a review

Anaerobic digestion enables waste (water) treatment and energy production in the form of biogas. The successful implementation of this process has lead to an increasing interest worldwide. However, anaerobic digestion is a complex biological process, where hundreds of microbial populations are involved, and whose start-up and operation are delicate issues. In order to better understand the process dynamics and to optimize the operating conditions, the availability of dynamic models is of paramount importance. Such models have to be inferred from prior knowledge and experimental data collected from real plants. Modeling and parameter identification are vast subjects, offering a realm of approaches and methods, which can be difficult to fully understand by scientists and engineers dedicated to the plant operation and improvements. This review article discusses existing modeling frameworks and methodologies for parameter estimation and model validation in the field of anaerobic digestion processes. The point of view is pragmatic, intentionally focusing on simple but efficient methods.