The industries of the future in Mexico: Local and non-local effects in the localization of “knowledge-intensive services”

The current characteristics in the global economy have defined “knowledge-intensive services” (KIS) as part of the so-called “industries of the future” due to the attributes of their employment and central function in the development processes in science, technology, art, and culture. This study outlines as a central hypothesis that the localization of KIS depends on different factors according to the type of knowledge being developed (analytical, synthetic, and symbolic). The main objective in this work is to explore the spatial economic factors associated with the localization and changes (positive and negative) when using KIS in the “national urban system” in México between 2004 and 2014. To do so, the services sector is defined according to the “intensity” and the “types” of knowledge that they develop. An analysis of spatial econometrics is carried out that distinguishes between the geographic (local) effect and the spatial (non-local) effect of the independent variables using data and microdata from the period 2004 to 2014. The results partly correspond with the central hypothesis of the study and offer possibilities of public policies to take advantage of and to promote the benefits of KIS, especially regarding cities in developing countries looking to become part of the 21st century economy.     

Extracellular Polymeric Substances Produced by the Thermophilic Cyanobacterium Gloeocapsa gelatinosa: Characterization and Assessment of Their Antioxidant and Metal-Chelating Activities

Cyanobacteria, particularly thermophilic strains, represent an important potential source of EPSs, harboring structural complexity that predicts diverse and specific bioactive potential. The thermophilic cyanobacteria Gloeocapsa gelatinosa, isolated from a natural hot source in Ain Echfa (Tunisia), was cultivated in a cylindrical reactor, and the production of biomass and EPSs was investigated. Results revealed that the strain is amongst the most efficient EPSs producers (0.89 g L⁻¹) and that EPSs production was not correlated with the growth phase. EPSs were sulfated heteropolysaccharides containing carbohydrates (70%) based on nine different monosaccharides, mainly mannose (22%), and with the presence of two uronic acids. EPSs were formed by two polymers moieties with a molecular weight of 598.3 ± 7.2 and 67.2 ± 4.4 kDa. They are thermostable in temperatures exceeding 100 °C and have an anionic nature (zeta potential of −40 ± 2 mV). Atomic force microscopy showed that EPSs formed multimodal lumps with 88 nm maximum height. EPSs presented high water holding capacity (70.29 ± 2.36%) and solubility index (97.43 ± 1.24%), and a strong bivalent metal sorption capacity especially for Cu²⁺ (91.20 ± 1.25%) and Fe²⁺ (75.51 ± 0.71%). The antioxidant activity of G. gelatinosa EPSs was investigated using four methods: the β-carotene-bleaching activity, DPPH assays, iron-reducing activity, and metal-chelating activity. EPS has shown high potential as free radicals’ scavenger, with an IC₅₀ on DPPH (0.2 g L⁻¹) three-fold lower than ascorbic acid (0.6 g L ⁻¹) and as a metal chelating activity (IC₅₀ = 0.4 g L⁻¹) significantly lower than EDTA. The obtained results allow further exploration of the thermophilic G. gelatinosa for several biotechnological and industrial applications.     

Decapsulated Artemia Cysts: A Suitable Dietary Supplement for Juvenile Tench (Tinca tinca L.)

There are no specifically formulated dry foods for tench (Tinca tinca L.), which forces farmers to use diets formulated for other fish species. This has major drawbacks, such as high mortality, slow growth, and body deformities. A 120 day experiment was performed with five-month-old juvenile tench (initial mean weight: 0.388 g; total length: 31.78 mm) to evaluate decapsulated Artemia cysts as a supplement to a dry diet for other fish species. Three treatments, differing in the daily supplement, were tested: 1,800 freshly hatched nauplii, 1,800 cysts, and 300 cysts per g of tench biomass. Final survival ranged between 95.3% and 97.9%. Juvenile tench that received the supplement of 1,800 decapsulated Artemia cysts had a specific growth rate (1.28), weight (1.83 g), and total length (52.30 mm) significantly higher than those with the same amount of nauplii. The lowest supplement (300 cysts/g of fish biomass) allowed significantly lower growth and higher condition coefficient (1.40) than the rest. Animals with body deformities (1.06%) were only recorded in the groups that received the lowest cyst supplement. Results showed Artemia cysts are a suitable dietary supplement for juvenile tench, being an advantageous alternative to live nauplii.     

Intensive rearing of juvenile crayfish (Pacifastacus leniusculus,Astacidae) during the first 6 months: effects of size grading

Recent advances in crayfish feeding have enabled the development of size grading studies from the start of first‐feeding. A 180‐day experiment aimed at intensive rearing of Pacifastacus leniusculus was carried out under controlled conditions, evaluating the effects of size grading at two different periods from the onset of exogenous feeding. Stage 2 juveniles were stocked in fibreglass tanks at a density of 100 m², and fed a dry diet for salmonids combined with restricted amounts of Artemia cysts. Five groups were tested: no grading, grading at 60 days (large and small size) and grading at 100 days (large and small size). After 6 months, no significant differences were found in the survival among groups (mean: 73.06%). The highest final growth (pooled results from upper and lower classes: 17.39 mm carapace length, 1.43 g weight) was achieved by the crayfish sorted at 60 days, showing significant differences from the ungraded group. Smaller crayfish graded at 60 days grew significantly faster than smaller crayfish graded at 100 days. The food conversion ratio was lower in the graded groups (mean: 2.64), showing significant differences from the ungraded group (3.23). This study shows that size grading allows a better performance and an improved feeding efficiency.     

Successive grafting confers juvenility traits to adult Spanish red cedar (Cedrela odorata Linnaeus): a tool for the rescue of selected materials

New Forests - Spanish red cedar, Cedrela odorata L. (Meliaceae), is a valuable timber tree in tropical American forests. Existing demand for elite individuals endangers the conservation of...     

Aboveground biomass,transpiration and water use efficiency in eucalypt plantation fertilized with KCl,NaCl and phonolite rock powder

Potassium has important physiological functions in eucalypt plantations, increasing their productivity when applied to soil via mineral fertilizers. There is interest in identifying alternative sources to KCl owing to its high cost and limited reserves. The aim of the study was to test the effect of replacing KCl with NaCl and phonolite rock powder. Two comparisons were made: (1) application of 283 kg ha^?1 of KCl compared with that of 2125 kg ha^?1 of phonolite rock powder (equivalent to 170 kg ha^?1 of K₂O in both treatments); (2) application of 139 kg ha^?1 of NaCl compared with that of 183 kg ha^?1 of KCl (equivalent to 2.33 kmol Na and K, respectively). Radial growth, soil water content, leaf water potential (Ψ), accumulated transpiration, stem volume and biomass increment, as well as water use efficiency (WUE) were evaluated. In the first comparison, both fertilizations presented equal values for all characteristics evaluated. In the second, the accumulated transpiration in trees fertilized with KCl was 17% higher than that in plants fertilized with NaCl. In contrast, the WUE was 20% higher in the trees fertilized with NaCl than in those fertilized with KCl, reflecting the lower water consumption for the same increment in stem volume and biomass. We conclude that phonolite rock powder and NaCl are possible substitutes for conventional K fertilization performed with KCl.

     

Effect of combined stress (salinity + hypoxia) and auxin rooting hormone addition on morphology and growth traits in six Salix spp. clones

New Forests - Willows plantations development could be an alternative for hydro-halomorphic soils but it is limited by combined stress salinity?+?hypoxia (main stressor under...