The determinants of urban (un)employment duration: evidence from Barcelona

This paper analyses the determinants of employment and unemployment spells in an urban area. Using data from a random sample of labour force participants in Barcelona, we find that individual, firm, regulatory and macroeconomic factors all affect urban (un)employment duration to a certain degree. Also, national and urban (un)employment exhibits the same shape in the baseline hazards and has similar macroeconomic and regulatory drivers, being the individuals’ characteristics the main source of difference we can identify. Consistent with the matching theory, the predicted hazards indicate that the likelihood of finding a job and of being fired is higher and lower, respectively, in the city of Barcelona than in an average Spanish location.     

Evaluation of thermal comfort using combined CFD and experimentation study in a test room equipped with a cooling ceiling

This paper reports a full-scale experimental campaign and a computational fluid dynamics (CFD) study of a radiant cooling ceiling installed in a test room, under controlled conditions. This research aims to use the results obtained from the two studies to analyze the indoor thermal comfort using the predicted mean vote (PMV). During the whole experimental tests the indoor humidity was kept at a level where the condensation risk was minimized and no condensation was detected on the chilled surface of the ceiling. Detailed experimental measurements on the air temperature distribution, surface temperature and globe temperature were realized for different cases where the cooling ceiling temperature varied from 16.9 to 18.9 °C. The boundary conditions necessary for the CFD study were obtained from the experimental data measurements. The results of the simulations were first validated with the data from the experiments and then the air velocity fields were investigated. It was found that in the ankle/feet zone the air velocity could pass 0.2 m/s but for the rest of the zones it took values less than 0.1 m/s. The obtained experimental results for different chilled ceiling temperatures showed that with a cooling ceiling the vertical temperature gradient is less than 1 °C/m, which corresponds to the standard recommendations. A comparison between globe temperature and the indoor air temperature showed a maximum difference of 0.8 °C being noticed. This paper also presents the radiosity method that was used to calculate the mean radiant temperature for different positions along different axes. The method was based on the calculation of the view factors and on the surface temperatures obtained from the experiments. PMV plots showed that the thermal comfort is achieved and is uniformly distributed within the test room.     

The multiColl Package Versus Other Existing Packages in R to Detect Multicollinearity

Computational Economics - The main goal of this paper is to show the advantages of the multiColl package in R, comparing its results with other existing packages in R for the treatment of...     

Nanogel-modified polycaprolactone microfibres with controlled water uptake and degradability

In this work we prepared composite poly(caprolactone) (PCL) microfibres decorated with temperature-sensitive poly(N-vinylcaprolactam) nanogels by an one-step electropsinning process. Microfibres with variable internal structure were prepared by using two different solvent systems: methanol/toluene (Me/Tol) and chloroform/dimethylformamide (Ch/DMF). Our experimental data shows that the nature of the solvent mixtures allows obtaining microfibres with different morphologies: Microfibres with nanogels on the fibre surface (Me/Tol) and microfibres with nanogels in the fibre interior (Ch/DMF). The morphology of composite fibres was visualized by scanning electron microscopy (SEM) and their properties investigated by differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and contact angle measurements. The results show that combining hydrophobic poly(caprolactone) with hydrophilic nanogels leads to microfibres exhibiting controlled swelling in water. Additionally, the thermo-sensitive properties of the nanogels are maintained whether they are on the surface or inside of the fibres. The presence of nanogels in the fibre structure also allows regulating their degradability.     

Synergistic antioxidant and antibacterial activity of rosemary plus butylated derivatives

Antioxidant and antibacterial activity of a methanol rosemary extract (RE) containing 30% carnosic acid (CA), 16% carnosol (COH) and 5% rosmarinic acid (RA) was studied in vitro alone and in combination with the antioxidant food additives butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). The antioxidant efficiency of the extract, CA, and RA, was determined by a kinetic analysis of the 2,2-diphenyl-2-picrylhydrazyl hydrate radical (DPPH·) scavenging activity. RE showed two different rate slopes in the reduction of DPPH· vs. time curve, which correlated with the distinct behaviours of RA and CA; pure RA reached the plateau more rapidly than CA. A synergistic antioxidant effect between RE and BHT was demonstrated by isobolographic analysis and a synergistic interaction of RE with BHA to inhibit Escherichia coli and Staphylococcus aureus growth was observed. Therefore, rosemary not only enhances the antioxidant efficiency of BHA and BHT, but also the antibacterial effect of BHA; allowing a decrease from 4.4 to17 folds in the amounts of the synthetic compounds used.     

Candida rugosa Lipase Supported on High Crystallinity Chitosan as Biocatalyst for the Synthesis of 1-Butyl Oleate

Lipase from Candida rugosa was immobilized onto chitosan using four different protocols. The variation of crystallinity (5.57–92.86%), which was a result of thermal treatments and crosslinking of the chitosan, influenced the protein load (7.46–25.15 mg g^?1 chitosan) and protein load efficiency (21.67–41.68%) for immobilization assays made with identical lipase solution concentration (1.3 mg of protein/mL). The effects of protein load (10, 30, 50 and 70 mg of lipase), reaction temperature (30, 40, 50, 60, 70 °C) and substrates molar ratio (0.05–0.30 M) have been studied in the butyl oleate synthesis in iso-octane when water activity of the free and immobilized enzymes were fixed around 0.53 ± 0.04. The catalytic activity of the immobilized lipase has also been tested. The Ping–Pong bi–bi mechanism with dead end complex of n-butanol was found to fit the initial rate data. The values of the apparent kinetic parameters were determined by graphic and parametric method as: V _max = 18.2–19.0 mmol min^?1 g^?1; K _{M; Acid} = 0.599–0.640 mol L^?1; K _{M; Alcohol} = 0.128–0.149 mol L^?1; and K _{i; Alcohol} = 1.933 mol L^?1.     

Optimization of freezing parameters for freeze-drying mango (Mangifera indica L.) slices

Today, there is an increasing trend toward consuming healthful food products, and dried fruits are one option for obtaining desirable nutrition in dehydrated products. Proper drying method selection is important for minimizing quality losses. Lyophilization (freeze-drying), a technique that removes water by sublimation at low temperature, can produce excellent dried products. Fast vacuum induction during freezing has been proposed as a way to control ice nucleation and to obtain enhanced lyophilized pharmaceutical products. However, this technique has not yet been applied to food freeze-drying. The aim of this work was to evaluate the effects of the freezing rate (0.4, 0.25, and 0.1°C/min), the minimum chamber pressure during vacuum-induced surface freezing (900, 700, and 500?mTorr) and the sample temperature at which the induced vacuum was applied (0, ?2, and ?4°C) on the total process time, final moisture content, rehydration capacity, total color difference, and total polyphenol content during the lyophilization of mango (Mangifera indica L.) slices. A Box–Behnken design with three factors at three levels was used to design the experiments, to generate the polynomial equations relating the dependent and independent variables, and to determine the optimal operational conditions. The results highlight the reduction of total process time (30%) at high freezing rates and the influence of the tested operating conditions on freeze-drying optimization. It was found that the optimal conditions that satisfy commercial quality goals were pressure between 500 and 650?mTorr, temperature between ?2 and 0°C, and freezing rate values close to 0.4°C/min.     

Factors affecting hospital admission and recovery stay duration of in-patient motor victims in Spain

Hospital expenses are a major cost driver of healthcare systems in Europe, with motor injuries being the leading mechanism of hospitalizations. This paper investigates the injury characteristics which explain the hospitalization of victims of traffic accidents that took place in Spain. Using a motor insurance database with 16,081 observations a generalized Tobit regression model is applied to analyse the factors that influence both the likelihood of being admitted to hospital after a motor collision and the length of hospital stay in the event of admission. The consistency of Tobit estimates relies on the normality of perturbation terms. Here a semi-parametric regression model was fitted to test the consistency of estimates, concluding that a normal distribution of errors cannot be rejected. Among other results, it was found that older men with fractures and injuries located in the head and lower torso are more likely to be hospitalized after the collision, and that they also have a longer expected length of hospital recovery stay.     

Possible Ecological Role of Pseudopterosins G and P-U and SECO-Pseudopterosins J and K from the Gorgonian Pseudopterogorgia elisabethae from Providencia Island (SW Caribbean) in Regulating Microbial Surface Communities

The gorgonian Pseudopterogorgia elisabethae collected at Providencia Island (Colombia) has an unfouled surface, free of obvious algal and invertebrate growth. This gorgonian produces significant amounts of the glycosilated diterpenes pseudopterosins and seco-pseudopterosins (Ps and seco-Ps). Our previous experiments have shown activity of these compounds against eukaryotic (human cancer cell lines and Candida albicans) and prokaryotic cells (Staphylococcus aureus and Enterococcus faecalis). However, the potential role of pseudopterosins on the regulation of the fouling process is still under study. We evaluated the activity of these compounds against bacteria isolated from heavily fouled marine surfaces as an indicator of antifouling activity. Additionally, we assessed their activity against bacteria isolated from P. elisabethae to determine whether potentially they play a role in preventing surface bacterial colonization, thus impairing presumptively the establishment of further successional stages of fouling communities. Results showed that Ps and seco-Ps seem to modulate bacterial growth (controlling Gram-positive bacterial growth and inducing Gram-negative bacterial associations). We thus hypothesized that Ps and seco-Ps may play a role in controlling microbial fouling communities on the surface of this gorgonian. By using bTEFAP and FISH we showed that the most abundant bacteria present in the microbial communities associated with P. elisabethae are Gram-negative bacteria, with Proteobacteria and Gammaproteobacteria the most representative. To evaluate whether Ps and seco-Ps have a direct effect on the structure of the bacterial community associated with P. elisabethae, we tested these compounds against culturable bacteria associated with the surface of P. elisabethae, finding remarkable selectivity against Gram-positive bacteria. The evidence presented here suggests that Ps and seco-Ps might have a role in the selection of organisms associated with the gorgonian surface and in the regulation of the associated bacterial community composition.